What Causes Numbness And Pressure Around Breast?

hi..i am getting numbness around my left breast and seems like it moves to my back and the feeling of a little bit of pressure underneath left breast...i am getting scared. it started about 3 weeks ago but its been worse the last 2 days. It is now a constant numbness. Do you know what could be causing this? I keep thinking its my heart and its starting to scare me