What Causes Radiating Pain From Below Breast To Back?

I have been having pains under my breasts in the lateral chest for almost 2 weeks. Sometimes on both sides and all the way across and sometimes just on the left side. I have also been belching more than I normally would. Sometimes the pain shoots all the way to my back. It has begun to affect my sleep. I have suffered from diverticulitis and am on a prescribed heartburn medication.