The heart has no pain nerves so its felt in other parts of the body, its called referred pain. Everyone heard about feeling it in the left arm. A heart attack is a dull pain and pressure feeling if its felt at all. Its often described by saying it feels like an elephant sitting on my chest. I never heard it described as a sharp pain. Sounds like a respiratory issue. Of course and aortic dissection is a sharp pain which killed John ritter, but thats pretty much a rarety and very painful, so no worries. I dont know what it is but Ive had pains when I take a deep breath and eventually goes away. If you are very concerned then theres always the ER. Your call as you know what it feels like.