Started my period today and it's usually heavy the first day or two but today i've had 3gushes with not much in between. looked like half a cup.worry?

ER: Any sudden gush of vaginal blood should be evaluated and you should be examined ASAP. I advise ER or UC center.

Yes.: Normally, I would say "no worries" unless the problem persists, recurs or has other symptoms like dizziness. But variations on Ehlers-Danlos syndrome can affect the strength and stability of blood vessels, including those of the uterus, which can progress from heavy bleeding to hemorrhage. Get prompt medical care, then see a Gyno for appropriate treatment to help control menstrual bleeding.