Needing some help.

I have pcos and have been on metformin for a couple of months now. In that time I've been poked and proded up the hoohaa a fair bit having tests. I believe one of the tests caused a period to come early. Yesterday i had to go for a smear test and it was surprisingly easy this time round and i never even had any bleeding. Later in the day i had sex and this morning have started bleeding and i dont know if its from the smear test or if its brought another period on. Im worried that the metformin is making my period come every couple of weeks rather than normal amount if time between each one