HELP Plan b

The first time I took plan b nothing out of the ordinary happened. The second time I took it just to be causeous (there was stuff out side Condom not sure if it was mine or his) took within an hour of sex. Two days later I started bleeding, at first it was very light I didn’t need a tampon ( thought I was spotting) and it happened for 3-4 day’s getting heavier. It’s been a couple weeks and I don’t know if it was plan b making me bleed or implantation. Should I take a test?