Double period

Kat
So I had my period on time, then about 10 days later (the day that glow said I started ovulation) I started another. It was like a normal period, but without the cramps (I've been getting really really bad cramps for the first 2 days for a few months now). It ended on the last day of ovulation. What should I do? What could be the cause? Should I be worried?