Did the vet do a skin scraping and/or bacterial swab? Or was the sore spot at least swabbed and looked at in clinic?
Bunnys are tricky when it comes to antibiotics, you need to find out what kind of bacteria youre dealing with before the bun goes on antibiotics otherwise you will just end up with a bun thats immune to certain antibiotics.
If its mites the revolution should have dealt with it if it was dosed properly.
A sweater will still prevent them from scratching at the area if they dont eat the sweater. Sure beats having to use a cone.
I've got some pics in this thread on the bunny burrito.
The trick is to get it snug around their neck (not in a strangle kinda way) so they cant slip their head into the towel or body out.