Wound that won't heal

I've been fostering a dog for just over a week. Information about her is sketchy but she seems generally well. She came with some sort of wound on her face which is seeping pus. A note said that she has had it for a while but it won't heal despite many vets visits and antibiotics. We don't think anyone could have been giving tablets regularly though.
We took her to the vet who put her on antibiotics for 7 days and gave her 3 more days worth as the wound is still seeping pus. She has another appointment on Tuesday. I wasn't told that I should do anything with the wound, but is there anything I can do to help this wound to heal? Thanks

3/8/19

Thanks so much. I looked up the tooth abscess online and it could be that. She is only eating soft food, or biscuits that have softened a bit. She won't eat larger treats unless they are broken into smaller pieces. We don't know the dog too well and thought maybe it's because she's old.

The tooth abscess seems to make sense and explains why it won't heal. I'm going to try to bring the appointment forward so we can get this thing healed.

4/8/19