This is one of my pet peeves, a doctor administering this med with no idea what the side effects can be and no idea what to do about them. Sigh, sorry for the rant, but really, this doctor should be doing the research not you.
Anyway, it sounds like side effects and/or antibody build up. You can battle these with pre-meds (and in your case, keep taking them for a few days to a week). Are you getting pre-meds? Tylenol, Benedryl, some sort of steroid? If not, you should be.
I would tell your doctor to look into this, and if he/she is unable or unwilling, to give you a referral to a doctor who cares.
49 years old, Crohn's Disease
Six resection surgeries, permanent ostomy, adverse reactions to Remicade, back on 6MP for maintenance, hoping for a long remission from this last surgery.