Heavy implantation bleeding or early period?

Gigi

I had an unusually early period (about a week early) that was fairly light in comparison to my usual periods. To be fair I have very heavy periods that are around the same consistency all five days. This one was very heavy for only one day and brown/normal flow with mostly clots for the rest. It lasted five days but again was light in comparison to my other periods.

I did take plan b earlier in the month and was wondering if this was messing up my cycle?

Taking a pregnancy test tomorrow, but was wondering if anyone else has experienced something like this before?