Jerry, I am glad you got some expert advice. Good luck with the 6MP (does it have a name?) and weaning off the prednisone!
Good luck with the wean off pred. Is he having you do labs before each drop in dosage...that's a must. The wean from 5 mg to 0 should be done super slow as that is the toughest part for getting the adrenals to kick back in. It's when most have flares. Some people to 0.5mg drops each week. I had to go 1mg every 2 weeks so it took 2 months. Did you bring up having the TPMT test to see if you could tolerate the 6MP? Imuran converts to 6MP in the body so I'm confused as to why he wanted to put you on that and not something entirely different.