Hi there,
It sounds like you've had a rough time with your wee Kitty. I'm a veterinary nurse, I wouldn't reccommend starting the anitbiotic paste on her. Is this from previous treatment? It is important to ensure that when treating with antibiotics that you complete the course as when humans take antibiotics.
Rather than a bacterial infection it sounds more like she might have ear mites, this can be easily treated using a spot on treatment such as advocate. Has she been treated for parasites previously? Fleas etc?
I'm sure the vets will get her sorted, but for now I wouldn't panic too much. As critter_crazy said, don't give her pamol, human anti inflammatories work differently to those given to animals and it could indeed be harmful to her!
If you are concerned about her being FIV +ve you could have her tested when she is at the vet clinic, it is a simple blood test and if she is negative you can vaccinate against the virus, there is a course of 3 vaccines to begin with and then you get it annually with the regular cat vaccine, well worth it! Even if she is FIV positive which is unlikely coming from a rescue society, she could sill lead a fairly normal, long and happy life. Often the main trouble with FIV +ve cats is that their immune system is a little compromised which means they pick up bugs a little more often, take longer to recover from infections and can develop dental issues, all this aside, they can still be fantastic pets and just need a little more attention.
Good luck at the vets tomorrow!