Im having sharp pain in my left breast and im not sure why. It has been happening for awhile and sometimes i can't move it hurts so bad.Its off and on through out the day and has been happening for awhile. Im only 21 i really don't think it's cancer. Also i haven't had a cycle in about 4 months im not pregnat i took a hpt and it was negative could this have something to do with the pain ? Is there some kind of breast exam i should do if so what am i feeling for ?