I went to pee and saw a 6-8in white string swimming in the toilet. all around the toilet. i've checked since and noticed small white worms in my pee.

Parasite: You have to go to a lab and provide a sample with these worms to have them identified so that the doctor can treat appropriately.

Threadworms? see doc: Thread worms (also called pin worms) can appear in the toilet when the urine washes them out of the vagina. They live mostly in the intestines, but come out to lay eggs around the anus, and in girls can travel from the anus into the vagina. The eggs can get under the fingernails from scratching, and then spread by those fingers. They are usually harmless and easily treated with a one dose med.