I have the same upper left <span style = 'background-color: #dae8f4'>breast</span>
. (under arm pit) I also feel it once and a while on the right side as well. I just recently changed jobs and am experiencin
g a lot of stress. Thought it could be a heart issue, however I'm only 34 and in pre
tty good shape. (Played high school sports as a kid) After readin
g the above I've come to realize that the in
creased stress and anxiety (new job, new baby, etc.) may cause you to worry at little more that you should.