I have a very sharp pain through my belly button to my vagina?

first of all...

-i AM NOT SEXUALLY ACTIVE! im 15 and a virgin.

-i have had my period for like...3 years.

-i havent gotten my period this month yet, maybe its coming.

-this has happened to me before & it went away after like 1 day.

Ok, so i have a very sharp pain and it feels like its in my bellybutton and just shoots down to my vagina. it hurts really badly. i went to a football game last nite with my friends and maybe i wasnt drinking enough water? im not sure. all i had was a juice. but i drank water when i got home. like at 10 pm. today, in the morning i went to go pee, & i felt a super sharp pain and i cud barely pee without holding my stomach. also last night after the game i went to sleep and felt a sharp pain when i moved....is it a sign my period is coming? it worries me because it relle hurts. also i cant stand up straight because i will feel the pain. what cud be the cause of this?

thanksss.