lump near shoulder

Hi.  I have a very rambunctious 9-month-old puppy, who recently jumped up to greet me, and her nails were so sharp, she REALLY hurt me above my left breast, almost to the shoulder.  (We have since gotten her nails trimmed!)  She left a bruise, and one night, I touched the bruise and, to my surprise, found that underneath that bruise was a pea-sized lump.  It is in a place that one would  not notice when doing the regular breast exam, because it disappears when you raise your arm to do the exam.  Of course, I'm scared.  It has been EXACTLY one year since my last breast exam, & I will be calling tomorrow to arrange for my next one.  My chiropractor said it's probably a cyst, and a friend suggested it's scar tissue.  The bruise has all but disappeared, but the area still hurts to the touch (the same kind of hurt that any bruise causes when touched), and the lump is still there.  Someone, please calm my fears!!!

[Cleveland Clinic]

Dear rosiesluv12, Over the internet it is impossible to totally reassure you regarding this lump without ability to further evaluate including physical exam.  This could in fact be the result of the injury, however without further evaluation it is impossible to say for sure.  Having it checked is the appropriate next step.