No idea, sorry.
If it get really bothersome for you, maybe go to an urgent care or go and see your primary care doctor. (I am guessing your GYN is out until Monday.)
Well I once I had strange period that lasted. Over 10 days while on the pill and I went in and they made me go on a higher dose and it went back to normal. I was on orthotrycycline lo and they put me on the regular one, so u might just need to change the pill up I would not worry to much till u talk to your doc make sure your taking your pill at the same time everyday too it is very important good luck