Hey, I had the same issues when I brought Tsuki home from the gentleman I bought her from. My vet immediately put her on baytril for 2 weeks, the symptoms got better, but then reverted by the end of the 2 weeks. I took her back and my vet did a blood test with the results being pasturella. We immediately started her on a higher dose of baytril and penicillin shots every other day. She had to be weight checked every week to alter her doses since she was growing pretty rapidly. We finished the pen shots and kept her on baytril for a few more weeks. When Tsuki decided she no longer wanted the baytril, I stopped (she took it very easily up to then) and waited to see if it came back. Thankfully it hasn’t (chalking it up to her young bunny immune system), but the vet warned it is a possibility it could come back or it might not.
it’s a very scary thing to go through, but with lots of love and attn your bun should be ok. If you have other buns you should keep them separate, because it is contagious (and very rarely humans can get it to from what my dr said)
Hope this helps a little!