Looking for advice!

I'm. It usually not a cat person, but after saving Socket, a young tabby from a car engine, I'm lost with some of her behaviour and I'm hoping someone an help. While I'm petting her, she'll occasionally start yowling and acting like I'm pulling on her tail. She'll hiss, then get u and try to get comfortable again, yet continue yowling and hissing. She shakes retry bad when this happens too. I've also seen her do this when using her litterbox, and just earlier a nothing at all. I'm stumped and could really use some advice.

First, after her rescue, did you take her to see a Vet to make sure she is AOK?  Whenever you get a new cat/kitten, first thing you should do is get them checked out because they could have parasites, diseases, etc.  And, of course, depending on their age, they may need their kitten vaccines.

Assuming you have done the above, when she yowls and hisses, does she also lick and try to bite at her tail?  If so, she may have something called Feline Hyperthesia, This is, of course, just a guess on my part. It was syour mentioning the "pulling on her tail" part that caught my eye, because hyperthesia seems to be centered on cats' tails, for some reason.  Here is a thread about it:  http://www.thecatsite.com/t/285067/update-on-binky-with-feline-hyperthesia-syndrome

If this doesn't seem the be the issue, and she HAS been to the Vet, you might try posting your concerns in the Behavior forum, as it might not be relateld to health at all. 

is she spayed? If she's spayed and otherwise healthy you may want to try to pet her from the neck up only and see if that doesn't help. Some cats do not enjoy being touched from the neck or shoulders down.

Unfortunately I can't afford to take her to a vet, but she seems to be well taken care of and in good health. (I think she was abandoned) I have been researching into FH since I got her because I couldn't figure anything out before posting. She doesn't seem to bite or lick her tail, but she does look back like maybe she's checking to see if someone pulling it.
And @hexiesfriend-I'm not sure if she's been spayed or not. And this little fits she has are triggered even if we're not petting her, or if we pet her head. So I don't think it's were we pet her.

If she appears to have been well cared for, is it possible that rather than having been abandoned, she got lost?  She may have a microchip in her.  I wonder if you could at the very least call a Vet's office and find out if they could at least scan her to see (at no cost to you).  If she does, they should be able to try to contact the owner of record.  Or you could take her to an Animal Shelter and they can check her for a chip, then you can take her back home with you (I presume)  You could call them first to make sure.

I don't know what to tell you about the behavior.  You said you have been reading up on FH.  Does it sound anything like that?