Dispy, your welcome man. But yeah it's probably from the way you put pressure on your elbows. I know I'm starting to get back pains from the way I sit and I'm only 22. Sucks! Get yourself one of those nice office chairs, with padded arm rests. That might help.

Zach -
yeah man Id stay away from stretching your fingers and plus cranking them. I know that can be a hard habit to break but it's probably the worst thing you can do to your hand. For warming up I generally just go through chromatics, and few easy licks to get myself warmed up. Other things you can do are th1 "1234" thing. I'm sure you've seen that somewhere. Rubbing your hands together and blowing warm air on them is good too, especially when it's cold. For your picking hand you can try different picking patterns to warm up. Not just alternating picking, but stuff like "d d u d d u d". Or whatever sequence you can think. Don't do it nochalantly, think about the pattern first then do it. Helps alot with coordinating the picking hand better.