Help please

I log all of my period start and end dates but this last period has been way different than any period I've had before. My period only lasted 2 days (11/27 & 11/28) and it was barely anything at all. I don't know if you would consider it light or spotting?? Other than changing it because I felt better to do so the next day I would have needed to because there was almost nothing on either pad. There was only blood when I wiped and it was clotty(clots are normal for me). But my periods are normally a medium flow and I have horrible cramps the first 1-2 days (also crampy off and on 1 week prior with tender breasts), and my period lasts normally 4-5 days. I didn't have any of that this time just the 2 days of clotty blood when I wiped. I took a pregnancy test and it said negative. Any ideas what the deal is? What I should do?