I have the rash bad. Took 5 day regimen of prednisone and it just started to ease off that last day. That was a couple weeks ago and the rash is back. All over my upper arms, chest, and back in the form of small acne looking bumps and all over my belly and on my thighs, calves and lower arms in eczema looking patches. Crappy thing is since I don't have the Steven Johnson's syndrome (or whatever it's called - the rash that rots your flesh) no one really cares how miserable I am. My rash didn't show up until after I'd been on Lamictal for 3months.

Get it checked out to make sure it's not the killer rash. For what it's worth Benadryl does nothing to ease the rash or symptoms for me

I hope you find relief and answers soon!