Jesus bro,bad timing on this,because normally Id shut you down for a bit.
Ok,first off,hydration,this is critical,as much Gatorade as you can stomach to prevent sympathetic cramping
Second,Ibuprofen is your friend
3rd have someone slowly rotate the arm for you at least twice a day,and I do mean slow,just enough to loosen the muscles not fast enough to risk tearing whats hurt
It sounds like a nerve,but it might be a tear,be very careful with this my son