If you are 25 and have multiple degrees, then you are smart enough to know that bright people aren't perfect. They make decisions that turn out not to be good for them. But they put things in perspective, and they move on.
You are letting your fears take over your thinking processes, and as a result, you are not thinking. For example, you would absolutely not be having HIV symptoms at this point, not at all! You have, probably, had things like a cold, a flu, a yeast infection or a strep throat over the course of your life, but you don't say "I have a virus in me," "I have a fungus in me," or "I have a bacterium in me." We all have microbes and bacteria in us all the time, and most of them are beneficial and keeping each other in check. So stop thinking of trich as "a parasite." There are lots of wonderful people whom you know well who have had trich or herpes or gonorrhea, and you're talking to many right here on Mamapedia. You are. Those are the odds. Everyone is going on with their lives, getting treatment and being more careful in the future. None of us are saying, "Who would want someone who..."
You need to stop harassing the man you slept with. It will do no good. You proceed with your own testing and health results in a sensible fashion. It's highly unlikely that you have contracted HIV - it doesn't go hand-in-hand with trich or any other STI. But making yourself a nuisance and having a restraining order issued is not going to help you at all.
Stop thinking about who is with another woman. And as for the man who wants to take you on dates - that's up to you, but you need to separate "dinner" from "sexual activity," not just now but in the future.
But it's true that you cannot calm down by yourself. You need professional help because this anxiety is going to be a much bigger problem than any STI will ever be. It will not go away by itself. You must call your doctor tomorrow and ask for a referral to a counselor who deals with these issues and who will accept your insurance. This is your priority - and it's just as important for your mental health as the doctor visits and tests are for your physical health. They are equally important. You cannot talk yourself out of this on your own. You cannot solve it through a man who provides you emotional support, or through your mother, or through Mamapedia. It's great that you have all of these different "spokes" in the "support wheel" but you need in-depth, objective, professional help. It's not forever, but it's necessary now.
You can get through this.