Depo shot

Brenda

So I'm concerned I got my first depo shot this month , and I got it a week before my period started , I have unprotected sex right after and before that . It's close to the end of the month and I have not gotten no period . But a day ago I had a few spots of blood maybe like 2 or 3 spots then I whent again maybe 10 mins after and it's was brown dark spots . And ever since it stopped and haven't seen anything then ? What's does this mean ?