You really should get it checked out. I had some problems with mine for years on and off and had to get some anti inflamatory meds from time to time. Doc said i had a minor injory to the rotator cuff. I was able to shoot my bow but other things would bother it. In April 2005 i fell thru an attic and hurt it bad this time. got an mri and was told i had a very large tear in the rotator that had to be fixed. surgery was terrable and rehab was no fun but my shoulder is 100% now and feels better now than my other one. hope yours is nothing serious.
Dan