Kayty, Ceftiofur is an antibiotic, but I think in this case, the wrong one.
kate82, here are my thoughts on your treatment
1. I like the Flunixin (which I believe is generic Banamine - and you can give injectable Banamine orally which is easier than IV)
2. Ceftiofur doesn't seem to be working like it should, so I think you need a change here. Talk to your vet about switching from Ceftiofur to Bactrim or some other SMZ/TMP that covers both staph (which I think is your problem) and strep.
3. Cold hosing and hand walking might help as well.
That said, I am NOT a vet, just a horse person who has been around the block a time or two.
At any rate, good luck and keep us posted on how things turn out.