I am too on Remicade, just had my third infusion yesterday. Give it time and it should work, hopefully soon for you. I have pancolitis UC, much bleeding, and the Remicade starting working slowly almost within 7 to 10 days, but you need to give it time. The prednisone should help as well. Just resting helps, eat very bland foods, low residue diet should help ease the pain while you are in your flare.
A multi-vitamin would be good when you are not having so much diarrhea, push the liquids, ask the MD for some advise on how to regain your strength. I too was very weak, but now on Remicade it's getting much better, but I just have trouble sleeping....I think I'm hitting the menopausal stage of my life, like I need that right now.
I wish you luck in getting better very, very fast.