Go to an animal feed store, the kind that sells stuff for horses/cows/goats. They use the same thing that you would buy at a pharmacy to kill internal parasites in humans, except it's dose and packaged for animals. (And may be apple flavored.)

You are going to have to deworm yourself twice. Because you will have killed the adult worms, but the eggs will hatch out and then you will be reinfected.

So deworm yourself now and then again in 3 weeks.