miscarriage??

hi, so im kindof concerned on if ive had a miscarriage and what the signs of one are. i took a plan b pill about 36 hours after a condom breaking right on the night of my suspected ovulation date, even though i knew there was a good chance that it was too late. a couple days later i started to bleed lightly and then it gradually got heavier and heavier, but would then fluctuate back and forth. i had read that it was sometimes normal after taking a plan b pill to experience light bleeding but not as heavy as i had it. i always get pretty extreme cramps and i had them for a couple days with the heavy bleeding, and then i passed what looked to be about a quarter sized (maybe slightly smaller) clot, which i have never done in my life. could i have gotten pregnant in the time before i took the plan b and then had a miscarriage a couple days later or could it just be a weird side effect from taking a pill like that? if anyone has any experience as far as miscarriages go or taking plan b your opinions would be greatly appreciated! also, if it is suspected is it necessary to go to the doctor or just a waste of money??