The depo shot can make your cycle off for some time after stopping it. People have reported up to a year after stopping it. I would think that the discharge is from stopping the depo shot. However if you are having unprotected sex there is a chance of pregnancy in which case you should take a home pregnancy test two weeks after when you believe you concieved.
Good luck
I would go get a test then if you are go to doc if not prob reg just rest all should be fine the shot messes with your body and it will take a wile to get back to normal I would think. Hope I helped