Chronic shoulder pain, and atrial infarct on ekg

This is long, sorry. I stopped working out a little over a year ago. I kept hurting my left shoulder (using weights too heavy over my head) so I would take a break for a week, then start again. I finally did it to the point where it was so painful, that I would lose my grip and I couldnt restart. It's been over a year, and I have constant pain. I rest it and just deal with it, but now this week, I've started getting sharp pains in my left upper back and worse when I breathe in. I work for a physician so I slipped in and did an Ekg just to rule out anything serious. I have normal sinus rhythm with atrial infarct...what! I pretty much have to not use my left arm for anything, and on certain afternoons, I have to position patients and move them from OR table to recovery. i get it done, but it hurts like hell...then for the next few days, Im in so much pain it makes me mean! I've been putting off going to the doctor but I guess I'm going to have to because trying to rest it has not worked. It's gotten worse to the point that you cant even touch my left shoulder, back, breast, or upper arm without getting smacked. I notice my hands and fingers get kind of purplish if I'm really running around at work. I've gained 20 lbs over the last year not working out. i cant even walk because swinging my arms is terrible. Any thoughts about this ekg thing? I just wanted to rule out cardiac but now kinda freaked.