Good luck with the Humira! It didn't work for me, but I know quite a few people who said it absolutely changed their lives and worked wonders for them.
I would think the hot flashes are from the Prednisone, I would get really hot really easily while I was on it. I never experienced it when I was on Humira.
Back pain I would think would just be from the Crohns in general? I get back pain all the time when I'm in a flare.
Feel better! :)