You can soak the affected foot in Tricide-Neo powder, labeled for fish, 5 minutes a day for about a week or so to treat the sores. Use nitrile or latex gloves so you don't get any on yourself. See this thread for more info.
For bumblefoot, I think you have to actually open the sore and remove the core. I've never had to treat for it, but I've seen alot of pics and such on here. The core looks like a black kernel of corn, pretty nasty. But I'm certainly no expert- good luck!
Perhaps your vet should try another antibiotic?? My hen had bumblefoot last year. I soaked her foot every day for 2 weeks in Tricide-Neo, and the only effect was that her bumblefoot got worse. IMO Tricide-Neo is a waste of money. I was lucky enough to find an avian vet, who prescribed the antibiotic Cephalexin for 21 days. It worked. He recommended no surgery on her foot due to the risk of introducing further infection and complications . Months later, the dead necrotic material inside her foot worked its way to the surface, where I was able to pull it out with tweezers. Because it left a hole, I used Neosporin on her foot and wrapped it with VetWrap for a week until it closed. It has been several months and her foot is good as new, no evidence of active bumblefoot. Cephalexin works. Again, it has been my experience that Tricide-Neo is expensive and a waste of money.