I just had my period last week. (12th-15th)

Last night and today I have had slight bleeding and cramping. Definitely not the amount of blood as I get during a normal period. This has never happened before. For the past two months, my periods have been irregular (about 10-11 days late both times) I am making an OBGYN appointment tomorrow to get it checked out, but what do you guys think is going on?