Period came 7 days earlier than scheduled?

Jinna • 21, model, EDD July 21 2016 with my first JellyBean. It's a girl!
I've been off BC for 5 months and my periods are never early nor late. Af is always on time. This is really unusual. 
I did the baby dance on Saturday and Sunday morning (10dpo) I woke up with some spotting. I just thought our baby dance was a bit rough. But on Monday it got heavier. No blood clots but I do have some cramping. I have no other symptoms which usually I'll have sore breast. What could cause my period to come a week earlier? I think this is too heavy to be IB. Should I take a test or is it pointless since I'm bleeding? Please help, thanks!