HELP MEE

i am really concerned right now and i might not make sense when i tell this story but oh well, i'm 14 and i had my period the 11th and i don't start till the 11th in october and i was in the shower washing my body and all of a sudden i feel this hard thing in my boob right under both of my nipples and they are sore and it hurts a lil bit when i touch and i squeezed to see if i was just imagining it being there and it's like a mass of something hard, like a pebble it feels like and i don't remember anybody in my family ever having breast cancer but i don't know what this could be or if it is just a period thing. comment if u know what it could be 😕