Hi I Am Experiencing A Pain In Chest When Ever

hi I am experiencing a pain in chest when ever I stretch or pump up my chest. Its not a chronic pain but a kind of irritation feeling. Also while sleeping sometimes when i change my position a feel this ache. also while getting up after sleeping. Also I am feeling a pain sensation type feeling in my left hand. This problem i faced 5 months back so at that time I have did 2D echo ,x-ray and all results are negative. Then I went to a doctor he told me that this might me myalgia case and prescribed me some set of medicine and after taking those drugs my pain went away. But again two days back I started feeling the same. I did some physical activity last week and from this Tuesday again I am feeling the same. I am really worried now why this is happening. Please suggest me something.. any specialist I need to meet.