I agree with Thatch.........just remember, sharp chest pains, and those that change with position and breathing, are almost never heart related. This does not mean that they are not terrible and bothersome, and frightening too. When something is askew in the chest, a common pathway of pain is to the arm and neck. This is called referred pain. Have yourself checked out. Sometimes just soaking in a hot tub will help, along with a heating pad, (after, of course.)
Sorry but this is a bit to vague. What medical problems? Heart related? If the pain is directly under your nipple it is not where your heart is. A heart attack can be painful. Pericarditus is painful. No sudden sharp pain or dull ache either. I think your problem lies elsewhere. As to your neck and shoulder you are probably out of allignment somewhere with the result of pain there. Car wreck? Bike accident, skate board maybe? I once had musco-skeletal problems in the upper part of my torso and arms because I had some bones out of place in my feet. Every step I took started a chain reaction that resulted in a kind of pain in the neck.
Computers are bad for you. Mousing, the posture you keep, etc.
I am not blowing your pain and ache off. I don't think that it is heart related but I do think you aught to get it checked out. An examination by a doctor might be in order. Do some checking around and find a good diagnostitian who lives for finding out what ails people. A body detective so to speak. You do not want any guesses being made and since people generally expect to be prescribed a medication when seeing a doctor most doctors will prescribe one. The best number of meds to be on is zero.
Thatch