Is it FLUTD?

I'm sick with worry again over my poor Max!  Took him in 2 weeks ago to vet because he was in and out of his box all the time, trying to pee.  All day at vet, couldn't get a urine sample.  No blockage.  Catheterized him, subcutaneous fluids, injection directly into bladder - no urine sample.  Did 1 week Clavamox, seemed to be getting better.  He peed that night.  No other symptoms - no blood in urine, pooping and eating fine, drinking.  Did x-rays, no stones.  POSSIBLE beginning of a stone, they said, but not clear.  Dx was possible FLUTD.  Trying to add more wet food to his diet, but he does not like it at all.  Also, he has bad allergies, so we don't have many options for food.

So, 2 weeks later, he's still peeing, but frequently in and out of box again.  Husband is taking him to vet this afternoon for a re-check.

How long does FLUTD take to resolve?  Does it frequently recur after antibiotics?

Poor guy has had SO MANY health problems

My cat has had urinary issues too. I have avoided this problem by feeding him only cooked organic chicken with broth (I boil the chicken) plus a little olive oil or coconut oil and brewer's yeast. Occasionally I cook fish for him too. When he has had issues - after getting into the dog food once- adding a small amount of vitamin c powder to his food helped him overcome the urinary troubles. Alternately Apple Cider Vinegar has helped (add to water in an eye dropper bottle - just one tsp vinegar then fill the bottle w filtered water and use eye dropper to administer) He used to not like wet food too. But he adapted. I used to give him canned food but had to stop. Dry food he cannot tolerate and brings on symptoms right away.

Baytril is often the antibiotic of choice for FLUTD/infections.  And yes it can recurr...

From what I've read, the UT issues seem to be one-off and non-recurrent?  We'd been feeding him Rayne Nutrition rabbit and squash on advice of the dermatologist to deal with his skin issues, and he loved it, but the company has had issues sourcing their product so I needed to go to something I could buy in the store, so we're doing Nature's Variety rabbit.  Tried duck and he didn't like that either.  Think we may end up going to raw food, as bothersome as that can be with the preparation.

Sigh.  So many problems in one little kitty.  But, I'm glad we have him and he has us!

I'm sorry to hear your kitty is having problems. My cat Rocky had 2 blockages about 4 years ago and most recently had a bout of inflammation only (cystitis), no blockage. They couldn't get a urine sample either, but he was going in & out of the box all day, peeing very little, but did have blood. He received an anti-spasmodic (prazosin) and pain meds (buprenex).

This was 2 weeks ago. I've been able to find a canned food he likes & I can add water to. He is still having some symptoms, though. He will go to the litter box 2x in a row. Once in the kitchen, then again in the living room. Thing is, a very good amt of pee is coming out. Like I can literally hear the stream hitting the litter! So symptoms can take some time to settle down. If your concerned, you can always give the vet a call or visit. 

So, I took him back in yesterday.  Vet couldn't even find his bladder!  They gave him some meds used for arthritis to calm the bladder and sent us home with some pain meds.  Then, last night, he started peeing blood.  At least he's emptying his bladder?!  My husband was supposed to take him in this morning for a urinalysis but couldn't get him in the carrier.  And of course, I didn't give him his pain meds because I told my husband to take it with him and have the vet tech dose him.

I'm pretty upset with my husband, but more worried about my cat.  Blood in urine is a sign of FLUTD, I've read.  I don't know if now I should take him to the vet immediately?  I called and rescheduled the urinalysis for tomorrow morning and let them know he was now peeing blood, but I don't know what to do, if this is an emergency or par for the course.  Any experiences to share?

I have experienced this with my cat several times over the years. I would mix a tiny bit of  vit -c powder and and a few drops of apple cider vinegar in with water in an eye dropper and give him one dropperfull at least 4x a day. Also put a few drops of vitamin e- from the liquid filled capsules on his paw to lick or in his mouth to help prevent internal scarring. 

I thought blood in urine was a sign of cystitis, more so than FLUTD, but maybe both? Ritz has never peed blood (only pooped) but did the litter box dance: do into litter box, squat, exit litter box. Go into litter box, squat, exit litter box. Ritz is prone to stress-induced UTIs, and has a diagnosis of FLUTD.
I've been feeding prey model raw (with the necessary nutritionally complete, secreting and nonsecreting organs, and bone) for several years, so she gets enough moisture in her food, with no additives. Since her diagnosis, I avoid fish and would suggest you do the same.
Concurrently with giving Rx medication, you might try using Feliway plug ins, playing soft music, lots of cuddles. I also supplement her food with l-theanine, a relaxant (green tea derivative).
If he's up to it, play time. As in humans, exercising reduces stress.
I'd call the vet and tell him/her Max is now peeing blood and couldn't get him into the cat carrier (been there, done that), and what would he suggest?