I've never dealt with parasites, but have you tried throwing up?.

Most likely, you've tried laxatives to have the parasites come out in the toilet, but throwing-up is another great way to get rid of stuff (it will definitely be the right way for your throat). Maybe the one in your throat hides in your esophagus (the tube that leads to your stomach from your throat).

Once I was at church and suddenly felt very sick and weak (it was something I ate at home but I had gone to church anyway).

A lady told me to get some straight, undiluted lemon juice on the way home. When I got home, I sat on my couch and let the juice get under my tongue.

I let probably about 2 drops touch the bottom of my tongue and IMMEDIATELY threw up three times like a machine gun one after another. I IMMEDIATELY felt better (100%) because I got rid of all of the sick stuff in my stomach (but it's a great way to clear your esophagus too).

Get a plastic garbage can from your desk, dump everything out and use the garbage can to throw up in (because you won't have time to run to your toilet).

After you throw up, rinse out your mouth and brush your teeth...because the stomach acid will rot your teeth from the throw-up.

Eat garlic to help kill parasites and to also kill the BAD bacteria (garlic doesn't kill the good bacteria/flora) in your gut (restoring your gut's health after throwing up....and take digestive enzymes, papaya, acidophilus yogurt, etc.).

the litters are easier to kill than the big ones
the question is how to take a big enough dose to kill a big one without accidentally killing yourself
fasting might help
have you tried a water fast?