What Causes Heavy Periods?

im 23 and having a very bad and heavy period im having to change my tampon every 30 to 45 minutes and thats while using a super with a regular one its every 10 to 15 minutes im having very large clots one of which pushed my tampon out of me when it passed. the last time i changed it as soon as i stood up blood went pouring down my leg and the tampon was already full within a minute. what could be wrong and should i go to a hospital?