Have you been tested? It would be a very good idea, especially since you have been sexually active with multiple partners.
There are lots of things besides STDs that cause the symptoms you are describing. It seems unlikely to me that it is an STD, but I am an uninformed, non-medically trained random guy on the internet. If you listen to me, you are being foolish.
Why don't you go see a medically trained person who can see you in person and give you definitive tests that will tell you for sure if you have an STD? There are clinics that will do this for free, or for very low cost.