is this normal?

I have just changed my brand of mini pill half way through. Before changing I had been on a irregular period for 2 weeks. I have been spotting for the last couple of days and then it suddenly stopped. Me and my boyfriend saw this as a good time to have sex as we haven't in over 2 weeks. After we did it I went to the toilet and I saw really red blood on the toilet paper. Is this normal to bleed after sex or is it because of the pill still?