Heartburn or heart problems??

Has anyone had such non stop heartburn that you feel it must be something more? I have a dull ache right under my breastbone, that feels like it goes all the way through to my back. I have been on Prilosec for 6 months or more and I thought it was working, but I feel like it may have gotten worse post Mirena. I would say I have that feeling more often than not. I started my period today, so not sure if that has anything to do with it. I am trying to be patient, but I can hardly function when I feel like I might drop at any second. I don't get alot of sharp pains just extremely uncomfortable feeling. It doesn't seem to matter what I eat or don't eat. I guess it may be back to the dr. to see if I have an ulcer or maybe a cardiologist? Who Knows, I don't want to waste my time or money and have all the tests come back normal. I want them to fix this!