Please help!!!!! big white clots in period, why?

my periods are steadily getting heavier, over the last 6 months, i cant wear tampax as they just come from clots (i know t.m.i.) im destoyed after an hour and have even ruined cloths within mins of cleanin up (sorry) also the clots arent just blood they can be white, pink and purple too, sorry but im worred and can explain it better through the annonimity of yahoo