Go back on the pred!
I suspect that there are a few people who are helped only by pred, and you and I are among them. When I relapse, I have to get IV-IG, plasmapheresis, and go up on the pred. When I’m in remission, I stay on a low dose of pred.–10 mg every other day. Yes, it makes me chubby–I could stand to lose 15 pounds–but I can walk and go to the gym.
I hope you find a great neuro soon who hooks you up with the right combo of drugs.