I'm 84 have a pacemaker and am having sharp pains in my chest while lying down. the pain goes away when i sit up. u have no other symptoms ?

Talk to your cardio: Your description suggests that it could be related to the pacemaker. I would recommend that you see the cardiologist who implanted the pacemaker to be sure there is no problem.

Benign Inflammatory: Musculoskeletal pain Most Likely. If you are not on Blood Thinning agent, you can try taking Anti Inflammatory like Advil/Aleve/Ibuprofen. But BEST thing is to ask your Cardiologist's advise.