It could be angina. I went for 1.5 months not knowing what this weird pain was across my shoulders. I noticed it first when I lifted a box and I thought "hmm, am I out of shape." Eventually I started experiencing periods of angina sitting on the computer, they would subside after 30-60 min until the night before my heart attack. That night I had pains in my shoulders and down both arms to my elbows. I remember laying on the ground trying to get some reflief. Because of my age (35) I was not thinking heart, but looking back now, I had all the warning signs (hypertension, high triglycerides, diabetes, very low HDL, high total cholesterol, sedentary lifestyle). I had the heart attack the next day at work, no discomfort from that, other than feeling like I was passing out, and leaning over did not alleviate it this time. I was lucky, because when you do experience angina at rest (unstable) its a dangerous thing to keep going. I do urge you strongly to have it checked out, if nothing else to rule it out. If you are right, then its not too late to set about changing and repairing the damage, if you are wrong then you have the peace of mind knowing that you are well.