I'm 24 and have never really suffered from any 'pain' problems. I stayed up all night for Christmas and then slept at my parents' house for about 6 hours. I woke up with a pain in my back, near the inside (spinal) edge of my shoulder blade. I'm guessing it's a result of sleeping in a strange position in a bed I'm not used to, but not sure exactly -what- the problem is. Pulled muscle?

It hurts if I breathe in too deeply, too suddenly, or when i cough/clear my throat. My range of motion is fine. It does, however, hurt a bit more if I'm bending forward. And also if I'm sitting down and turn my body to the left or right. Last night I slept in my own bed in a normal position for me, but when I woke up it still hurt just about as badly as before. I slept just fine, without being woken up by pain or anything.

Other general notes:
I'm underweight
I spend a lot of time at the computer and don't exercise