What Causes Light And Short Periods?

lilliansmommyandbrandonswifey: What could it be if I started my period on time but it s not like it usually is the first day I started it was light then the next day it was heavy and it was only heavy for one day now it s light again and I ve been on it for 3 days and I m about to stop and I usually go for 5 to 7 days