Im not on my period at all but i passed a blood clot the size of my hand and then started bleeding very very heavy.. im in so much pain. ?

Get seen now: Severe pain, that is not usual, plus heavy bleeding, needs to be evaluated right away. If you are sexually active, you could be pregnant and this is a miscarriage or it could be due to a tubal pregnancy. Please have someone take you to an ER now. Other causes are possible, but severe abdominal pain is always concerning and evaluation is best, sooner than later.