Need help figuring out what I have
3 weeks ago I went to the ER due to chest pain on my left side and I went again yesterday Xray, blood test and ecg clear both times. Blood test did show my mcv is 76 so little low but shouldn't cause chest pain. I haven't been to the gym in 3 weeks due to the pain. Pain is on left side chest then sometimes right side chest then both ribs, under left armpit. Pain is never constant but comes and goes almost like 'shocks'. I sleep perfectly fine and I can do pushups/pullups but do feel some pain after pushups to try not to. Any idea if it's costo or something else? I breathe perfectly fine, one doctor gave me acid reflux pills but that just gave me a sore throat. I did go for a 2 hour walk at night the other day and by the end of it my chest both sides tightened up. Im a healthy male.
TLDR:
Not sure what I have, clear tests, 5/10 pain that bounces around upper body randomly