help!

hey girls,

so my period is late. by 5 days. almost 6. i’m almost 16 and not sexually active. this has happened a couple of times by like a day or two but never this long. does anyone have any idea on what this could be? i’ve been stressed out to the max about it for a couple of days and i’m scared something bad might be happening. i’m getting cramps, back pain and (tmi) diarrhoea and i’ve been a bit gassy.