I’m not sure how sebatious adenitis is treated in rabbits, or if that is what your rabbit has, but one of my dogs has it. He gets it inbetween his front toes and it used to pop up 2-3 times/year and everytime we would treat with 10 days of antibiotics, shaving the area to get good margins, and and soaking it in an epsom salt solution once/day for the first couple of days. Everytime it would go away and everything would be fine for a while, but it would be back again. And it was quite a painful area for him to get it
Then I started working at a different vet than the one I was going to, and this vet said that she had just read a new article about using benzoyl peroxide (the alternative ingredient to salycilic acid in acne cream), as a preventative measure, on the area that they usually break out on. Low and behold he hasn’t had a break out in over a year and a half! I just put a pea sized amount of the cream on the area once a month and so far it’s completely preventing it!
If it does turn out to be sebatious adenitis, maybe get your vet to look into the use of benzoyl peroxide for rabbits. Obviously they can’t be ingesting it though, so that would be tricky with a rabbit…