Cat's cheek is raw, a little swollen & her whiskers fell out. It has not healed in about 3 months..?

This started right after she had all her teeth removed due to gum disease. We noticed it when we brought her home from the hospital and the cone collar was on her, and thought it had scratched her, or perhaps something during the surgery rubbed her raw. The Vet gave us a clear bubble gum smelling liquid (?) to hold on her cheek 2 x day, but it seemed to make it worse, so we stopped. Her whiskers grew back very short and thin, about 20% of regular size. There's no discharge (sometimes a little bloody if she rubs it), no nasal discharge, she has no allergies, and no infectious look to it. Her appetite is fine (!), she does not throw up, and has no indication of anything else wrong with her. Except once every week or so she'll sneeze 5 to 15 times in a row, then nothing. Is there anything we can give her or put on her cheek to heal this? The Vet does not have an answer, and I don't want to keep paying for test that turn up nothing. Has anyone experienced this?