I have chest pain. Upper side in left.

I'm having chest pain for few months now though it's not persistent. I feel like I can pin point it but not exactly and I'm having too much gas still I'm not sure if the pain is because of GERD. The pain is not severe it persist for 30 to 40 secs and sometimes for a min or two. Very few times I feel pain in lower right side...it's rare and mild. When I took a long breath once it pained and it was not that mild though not severe as it is very rare. I also have bad posture like from 3 or 4 years now. Now, the pain is like pressure or pinching I don't know. I'm also not sure if it's movement related or radiates to any parts of my body. I don't feel symptoms like dizziness, lightheadedness, and stuff like that. Sometimes the pain is not on the lower left side it's near the front shoulder like at upper side in left.