I don't understand this!

Hey ladies, so I'm 20 years old and when I get my period it always lasts 6-8 days. It's never been irregular, and always been the same pretty heavy flow. I got my period the night before yesterday, and it was heavy, I had bad cramps (all as usual). But the next day it was barely anything, just a light pinkish spotting and only if I wiped, and last night it was absolutely NOTHING coming out. This morning, it wasn't anything, but it was just a little, seriously the smallest amount of brown dried up blood. Why could this be? That's not normal for me!