help please! gut-ripping cramps and dizzy spells???

so this is my second or third day on my period, and my cramps can get pretty bad aorund this part of my period. Personally, my cramps can get pretty bad and hurt more than most women would agree. but this is a bit worse, the cramps are more frequent and if i stand for too long they so bad that i curl over while standing and sort of rest my chest on my legs in a squat. This morning, and a couple times in the afternoon after i stood up to fast i got really dizzy and had to grip the wall, my vision even blurred out for a few seconds. Anyone ever experience anything like this? theres no way im pregnant since i havent had sex in over a year.