Unusual period after PAP test?

I went for my very first PAP test 3 weeks ago, and I was supposed to start my period on Sunday, but it started on Monday and has not been right, normally after 18 hours I get horrible cramps I have to take Mefenamic for which will last about 12 hours, and it's usually a medium foe, but this entire period it has been extremely light. Has anyone ever had this happen before? My periods have always been 100% consistent, I just thought this is slightly odd, I'm going to try and see my doctor about it on Monday but I thought I would se if any ladies had an idea what it could be.