question: My husband just got back from a canoeing trip. He said he started experiencing a sharp pain between his shoulders on his back. This happened one time while hw was canoeing and then today when he got home he felt it again when he lifted an air conditioner to put in the window. It doesnt seem to bother him otherwise bit he said he never felt like this before. He just carried a 25 lb case down stairs and felt the sameain again. He checked his pulse and seemed normal. He does not have chest pain nor feel nausea. Do you think it is related to his heart or something with his muscles?