I'm a 15 year old female and just started gym class about one day later i felt a bump under my armpit, it is not above the skin but is under and more towards my back. Its a little tender. I poked a needle in it and a little white goo came out almost like puss. I'm not really worryed that it's breast cancer but i dont want to be to sure, but i'm worried of what it may be.
What may it be? please help.
Thank you a miillion,