I don't see anything relating to what your are describing for Tacrolimus other than in the context of an allergic reaction. If you are improving with a dose reduction then it seems safe to assume that Tacrolimus is the culprit. But, you are cycling prednisone as well (not sure if on your way up or down) so how can you be sure if that is not a factor, unless you've cycled it in the past without a similar reaction? If these doctors don't understand this drug but want to keep on using it wouldn't it be a good idea to get a consult with a doctor who does understand it? I'm on a lot of meds and have dealt with surprising reactions the root cause is still to be determined. Very frustrating. Hang in there.