i get pain under my armpit when i sleep the wrong way, with my arm up under my pillow. as for a lump.. ingrown hairs maybe the the issue, however they go away after a few days. it all depends. i would say dont worry about it, but if you are, then just go to the doctors and see what they say. my guess would be ingrown hair. they cause a lot of pain and discomfort when they are at the armpit
sounds like a swollen lymphnode or w.e....just means ur bodys fightin a sickness...or it could just be some odd puberty thing.
yer i thought it may have been that. i have been feelin pretty slack lateyl and i had a sore throat the other day
cheers