Thank you for taking care of this somewhat feral cat, she is very lucky to have you. What bothers me most about this is the fact that this wound has not healed in 2 months. It is possible that you are dealing with a bite wound that just won't heal with out medications, but it is also possible that it is something more then that. Lesions like this can change drastically in 2 months. Its possible that there is a foreign body under the skin. Its also possible that it looked like an abscess several months ago and that it has changed over the past 2 months. I realize your reluctance to have it rechecked but I think that is what would be best for your kitty. I would avoid the use of isopropyl alcohol on an open wound like this because it stings.
Hope this helps and keep me posted.
To add to Dr. Vicksman's post, we can't "prescribe" treatments for you over the Internet, so to answer your question about the GTS, you should contact your veterinarian about whether it is safe to use that product on the cat.
Secondly, although hydrogen peroxide is a great initial flush of wounds, repeated use can delay the healing process. H2O2 actually destroys certain cells that are essential for the skin to heal. Many people also consider the use of H2O2 to be uncomfortable for the pet (i.e. it stings a little as well).
Good luck with this and let us know how she does after you get her rechecked at your veterinarian.
Thanks for both of your advice. Lol yeah even though she is somewhat like a feral cat she's part of the family and I've had her since she was a kitten so I'm happy to take care of her, but know sometimes these type of cats are hard to take care off when it comes to medical issues. I actually had a chance to take a good look at the wound last night while Misty the cat was eating and it looks like it is crusting up which I think is a good sign because the vet we previously took her to said when a wound is in the process of healing it starts to crust up sometimes and the dead skin falls off, I don't know if that makes sense or not. Also the wound did look like it was healing well at one point and the skin looked like it was getting back to it's normal color the only reason the wound reopened was because of Misty's sister getting into a fight with her and accidently hitting it which in turn reopened the wound. As for the the GTS topical spray I will take your advice and call the original vet I took her to to see if that is a possibility of using it on her wound. Thanks so much for both of your professional opinions and God Bless you both.