Yes, drug prohibition causes all that shit.
Dude... this was incredibly stupid. But now it's done. The world won't stop spinning, but I know how bad it can be not to know if you catched a disease or not. Asking you why you did this doesn't help either, so I won't ask.
It's always the same... people trying to get their medication, but prohibition forces them to take dirty drugs (impurities etc.), buy their impure medication on a black market where it's very dangerous and then they even don't have the necessary tools to consume them... this system MUST come down. It will come down...
Get tested. There's a test that can be made immediately, but it costs a lot more than the "normal" tests. It's named something with "RNA" or "RN PCR" or something like this. It tests for the RNA of the virus I guess. I've had one of these tests myself, and I know how terrible it is not to know if you're positive or negative.
I wish you all the best. I really hope that everything is fine. Did you know those other two guys? Are they friends of you? Do they shoot up often? I can't imagine how this must be... I couldn't use a syringe that's been used by another person. I don't even re-use the syringes I use. Once I've injected with a syringe, I throw it away. But I collect them and then I bring them to the needle-exchange. It's great. You buy 30 syringes, bring them to the exchange and say "it's 50 syringes". Get 50. The next time you say it's 70, then 100, then 130, then 150, then 200, then 250, 300, 350, 400, 500... and abracadabra, you got a big supply of sterile equipment. Unfortunately, the needle exchanges in my country haven't heard ANYTHING of micron-filters ("wheel filters"). They have those "steri-filters" though... They have a membrane, but they don't filter much better than filter paper (for coffee for example) or a cigarette filter. I hope they'll get micron-filters in the near future, because in my country, the main opioid that's injected is not heroin, but morphine-pills. All those people who inject LOADS of fillers, especially micro-crystalline cellulose and talc... my goodness. A friend of mine knows someone who showed them a micron-filter, fortunately. I hope they'll think about it...
THEY DON'T HAVE NEEDLE-EXCHANGES IN EVERY COUNTRY IN THE USA?!? WHAT THE FUCK IS GOING ON ON THIS PLANET?! I guess I can be "thankful" for living in a european country that has needle exchanges in its major cities.