I broke my hand yesterday and got it cast today and when I try to sleep it hurts so badly IV taken tylenol (acetaminophen) but can't take anything else due to crohns?

Elevation. You might try elevating your arm above heart (mid-chest) level. On your back this takes a simple pillow under your forearm. Sitting or standing it is practically over your head, although, resting it on the back of a chair or sofa works, or laying your forearm on top of your head. You might also have the cast checked by the doctor to see if it is too tight. This pain should not last long, a day +/-.