Spotting issues

Okay, I haven't been on my period for about 8 months now, due to my current birth control injections, I receive every 3 months. But, I last week I had an embarrassing sex situation and its still bothering me. I am noticing that I have been spotting and its red and sometimes even dark brown and it's an odd smell. I believe it's an old egg but I'm still confused about it. Also I used the bathroom once and I saw something so crazy in the toilet. It looked like it could've been a baby that was forming. (Weirdist thing ever) but I'm all ears because I want to know what's going on and I want to make sure that I am okay