I'm so sorry to hear about your cat. I went through a similar thing about 6 weeks ago with my cat. She had an anal gland absess that opened up. It was a Friday night so I decided to treat it myself at least until Monday when a regular vet was open. Well my treatments went so well that I never did take her in to see the vet. What I did was give her Colloidal Silver in her water, I cleaned the area with Colloidal Silver and drained it as much as I could 2-3 times a day, after each draining/cleaning I would cover the area with coconut oil and oregano oil. I also used a suringe (sp) and shot some oil or oregano mixed with coconut oil into her mouth. Like I said she was looking so much better by the Monday that I decided just to keep on treating her myself and she was completely healed up within a week...something I don't think even Antibiotics could have achieved.
Good luck with your kitty...I hope she is feeling much better real soon.