Do you have neck or upper back pain? have you had an MRI of your neck or back? Do you smoke? Describe what the cramp feels like. I've had surgery on my cervical spine (neck) and I wake up with cramps, achiness, tingling in my forearms and hands. So my symptoms can be associated with those issues. I'm trying to find out what could be causing yours.
Good luck, to this day i have not found a Doctor who can tell me why i have these cramps also in hands, sometimes in one or other times in both,and they always start 10 to 15 minutes after eating, which makes no sense at all.I don't think Doctors this day in time know anything much, except how to write a prescription, to mask the problem: that's the reason we have so many people in pain today.I think it could be that after eating, your system pull's fluid, thus causing cramping,but i really do not know. I have had neck surgery, and four back operations, and is it all the medal causing this problem? All I know is no one seems to have any answers. So again Good luck, hope you find someone that can give you some answers.