Hi,i'm 16,am 1,71metres tall and weigh 55kg.i have had very normal periods since my first period but recently they have lasted for 15 days and resumed again after 6 days,lasting for 8 days so far.i wonder what could be wrong.i recently lost weight from a 60kg and i joined basketball where we train hard.also,i've engaged in oral sex.could it have contributed to the long periods?