Even though it's possible it could be a mass, I think if it's been 4 months you would have felt more than just pain at this point. Which it could be internally, but you don't mention anything about any other problems, breathing etc, which wouldn't be too far from your lungs. Are you sure you don't have GERD, It's possible an ulcer or inflammation of the upper digestive tract. Even though that is where the pain is.. it may be nerve endings you are feeling, so it could be gall bladder related, or anything to do with acid reflux. Without an exam in person it would be hard to pin point the exact cause of this pain. So yes, you should see your doctor. Any pain that comes on sudden without cause of injury should be explored by your doctor. So tomorrow, call for an appt. (Do keep me posted through PM-- would like to know how you make out)

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