Depo or pregnant?

Lauren

So I was on the depo shot for about 7 years. I got off of it to get pregnant. I had my daughter in June of 2018. I got the shot again the day I came home from the hospital. I'm due for it March 6th. I'm having bad stomach pains and just started bleeding. Not heavy but more than just spotting. Is this the shot or could it possibly be pregnancy?