Hi, I Got The Depo Shot On February 23rd. I

Hi, I got the depo shot on February 23rd. I was due for my second one on March 23rs but didn't receive it due to the side effects. I have yet to get my period since stopping &I now have a darkish brown discharge. I've been sexually active (with the same partner I have a child with) is this normal after depo or should I be concerned about pregnancy?