Deep issues with cat

So I have been going through some of the pages recently but just created the account since I do really need some ideas. 

I have had cats and kittens, and even a couple of ferals in my life and I thought I knew all there is about cats. But somehow I got a curveball and I am at my wits end. So I had gotten a dmh from the shelter as a kitten (of 3 months) who after some initial adjustment problems went along well with my current resident animals including an english bulldog (~2.5 yrs old) and a himalayan (2 yrs old). Now after a year, the kitten who is now full grown has gone ballistic. 

In detail, she (name's Tsee) hisses and scratches at everything and has already drawn blood from my resident himalayan Pipi and the bulldog Czar (more serious injury with Czar since she bit the folds of the skin and it is a painful process to for a bulldog to heal there). Thankfully both are well behaved and not aggressive so there was not much of a retaliation for Tsee. And I am not even writing about me, since I don't really mind bites too much. That was week 1. Since then I have tried Feliway, diazepam, bach's remedies, isolation treatments, excess love and fuss, the best foods. I have had her vet checked twice and there is nothing physiologically wrong. And this is for 3 months. I can wait longer, but my other pets are now starting to get snappy and I can't handle so much at the same time. 

As a kitten, Tsee was very sickly and had a perennial sneeze which got over later. Otherwise, she responded to petting, liked canned food and tolerated dry stuff as well, is spayed. I used to clip her claws but its getting harder. And if she uses teeth, there is not much I can do. And 3 months is a long time to be patient. 

I don't want to rehome her for a couple of reasons. 1. Why should anyone else face the same issues? 2. I have spent a lot of money, time and effort. Too much sunk costs now to let her go. It is almost a challenge. And I cannot in my mind dream of euthanizing a cat or a dog. I love my steaks but killing pets or resident animals is not me.

Changes in environment: there was a tree by my house which fell during a storm. Otherwise, its pretty much the same. There are no diseases or issues with my other animals. I have been to the behaviorist at the shelter but he is also lost. He has referred me to another who is more experienced (or knowledgeable) which will be my last resort, but the new proposed behaviorist charges a pretty hefty fee. I am not sure whether I can again afford a 500$ bill over the months. I might be forced to but I will consider and really appreciate any suggestions first. I have waited long, so a few days longer won't hurt.

Long message. But I needed to be detailed and clear. Hope it helps.

If she had a constant sneeze when she was a kitten, she may have the Feline Herpes virus. You might want to start giving her 250mg of L-lysine twice a day. That will keep the virus under check.

As far as the behavior, most of the things I would suggest, you have already tried. I am assuming she was spayed when you got her. The only other suggestion I would have is to Isolate her and slowly re-introduce her to the other pets.

I am gonna try out the L-lysine for sure. I do have space in my house so I can re-do the intros. I had never thought of this, since all my animals were well adjusted before something just snapped. Well worth a try.

the anti-cruelty here has behaviorists who will speak with people for free. have you tried the one in your area and/or gone to a cat-only vet? I find it hard to believe she would change overnight without a physical reason

I do have a cat only vet, but have not tried the anti-cruelty people (actually I did not know too much about this resource). I am pretty sure there is no physical reason. Not sure, how overnight the change was, as there could be subtle behavioral changes which I could have missed. I agree with you ^ and I don't think it can be out of the blue, but there could be a variety of factors such as a stray visiting our curb or something which in no way I can guess. 

The shelter behaviorist told me that this could be due to the stage Tsee is in (as in she may be trying to test out or testing out dominance behaviors). Or it could be something ingrained, which only got expression once the cat reached maturity. That said, there were always some quirks with Tsee but nothing really bad IMO. I live out in a quieter and less busy neighborhood, and while my bulldog and the himalayan would readily lounge in my little porche, Tsee would usually avoid going outside. The few times I actually tried taking her out cradled in my arms would result in her being terrified and absolutely clinging to me. 

Lastly, she is not doing too bad when left completely alone (i.e. just me and no other animals or unwanted stimuli). She eats, comes to me and even purrs at times. And there has never been any litterbox issues at all. And yes, she was spayed when I had got her (which was at ~2 months).

I wish I could suggest more for you. But if I knew all the answers, I could get $300 an hour as a consulting fee. The best thing to do is have patience and remember you have to convince her that it was HER idea to get along.

Thanks for the help people. I actually got through this...updates 

Neighbors spotted a coyote in the area near my house and the authorities got it away. I also re-did the intros a bit. Anyway, things are back to normal. I am not sure what exactly the reason was but my vet thinks it might just be the presence of the coyote which messed things up.

Great news!  Could also have been that tree falling - bizarre, but loud bangs outside have been known to spark just this kind of switch.  Re-doing intros is good in that instance, as the 'fright' gets blamed on someone (your pets for instance), so reassociation that they are all good is needed.

Glad it worked out!!

I would also like to add this.

Females are dominant of the 2 sexes, and around 8 months or so old, she will change out of her total kittenhood and more into a bossier cat.

It will be full blown by the time she is 1 1/2 or so.

It's fine, males know this and submit to it fine, so she knows she is established that way.

The coyote drama may have very well triggered some stress from her though, it makes perfect sense.