I would have occasional pain in the chest around the heart. At the stage you are in, I would get it after a good coughing fit due to allergies. At about 10 weeks it lasted for awhile and I got worried. I read up on it and believed it was probably related to brusing and damage to the ribs and the membranes/linings around them that happens to open up your chest. It's not a pain related to the heart. The rib/chest trauma can take a long time to heal completely. I still get an occasional pain after 18 months.