Smelly discharge?!?? 😰

So I had my period last week and had unprotected and unwanted sex with a stranger (yes that’s a problem but I’m already dealing with that) so I know that I’m not pregnant but I’m worrying about STDs...

Three days ago I found that my discharge, just when I finished my period, was a bit smelly and contained a bit of blood. I wasn’t that worried because it can happen I think. But now it’s still very fishy-smelling and the color is orange like if blood was mixed with clear discharge. I have menstrual cramps but I dont need a pad.

Also I have to mention that I used a menstrual cup during my period and one day I forgot it was there and I kept it in all night and all day... Now I just putted a tampon for like 5 minutes to see if there was any blood and when I pulled it out there was a bit of brown blood and it smelled. What is it?? Is it an STD or am I still on my period but it’s impossible...