Here's a strange one....

I've seen this before. Was a firefighter buddy of mine. During the day he was in constant pain but when he lay down the pain went away fast. Turned out to be the Brody ligament which keeps the bicep tendon located in the groove at the top of the humerus. When he would lay down the tendon of the bicep would relax and move back into position and take the pressure off the ligament and the pain would stop. They did surgery on it to repair it. He was off for 2 months and came back to work and within a week was injured again. Surgery again, 2 months off and came back. Within a week he was filing paperwork for medical retirement. It is your body's way of telling you "don't do that no more".