Chest pain. Should i be concerned.

I have been facing a pressure kind of pain on left side of my chest since 4-5months now. Initially when it happened, I was scared as I was gasping for Air. I work in night shift and was in a lot of stress during that time so I blamed it on that. Now, I still get the pain but it's more continuous. I can feel it through out the day. Very dim but a pressure kind of pain. The pain is usually on the right side of left breast and it gets little intense during night times ( my sleep time is usually around 5am in the morning as I work in night shift). When I put too much focus on anything, it starts beating fast and I feel pressure. At times I feel it for no reason. Can anyone please help me understand what I should be doing. Should I be concerned..