Aching Pain under left breast, difficulty catching beath!!

[lilbear72]

HI Around two months ago i noticed a strange feeling below my left breast. It felt sore if i bent down or turned to the right too far. I felt it on and off for a couple of months and then two weeks ago i went running and the pain got much worse and i thought it was my heart. I foound it soo hard to catch my breath. The rest of the evening an dnight wa spent with an aching pain right over my chest area and into my left shoulder and the continued difficulty in catching my breath. I then took a pain further down under my ribs at the left and am currently seeing my doctor about but that has now gone and yesterday i went running again and thew same thing happened. Sharp pains in my chest and the the next 12 hours spent with that dull aching feeling all over my chest and left shoulder. I was convinced it was a heart condition as my dad has a heart condition too so i went to my docotr today and she all she did was take my blood. She said oh it is probably just some kind of muscular problem but i am really worried as the aching feeling i can deal wioth but the not being able to cath my breath scares me and i still have it now, it has not yet gone away. I am worried it could be my lungs or heart or asmha or something and she will not do any tests. Does anyo0ne know if this is correct or should i get a second opinion? I feel awful going in as they make me feel i am wasting their time.