I have an 8 year old and we are preparing to redo our parasite cleanse. I have found a drnatura.com has a product called paranil junior for kids. Also there is a product that MH sells but it's rather expensive but it's a liquid as well as the paranil jr.
I am here online searching to see if anyone found the drnatura effective when I read your message.
My daughter was loaded with worms, when I discovered them last year. I saw them with my own eyes. It was devastating to be a mom and witness it. We went to the drug store and bought some pin-x, because it was just much easier for a young one to take than the Clarkia .
Just my opinion.
Best wishes to your son and you.
Take care and good luck!