Could be stomach related. As your stomach goes around over to the left there under the ribs. Try some Rennies or gaviscon, or an over the counter stomach acid inhibitor like omeprazole or nexium or pantoprazole for a few days and see if that relieves it. If it's worse when your tummy is empty, or after eating acidic foods (or wine etc) it's probably stomach. Likewise you get the pain and then eat something, drink some milk, and see if that relieves it.