A zapper and Dr. Clark's protocol. It'll work miracles. I'm pretty sure she even has a scaled down version for young'uns. The PDF is available here for download. Try the second one listed though, the first link hasn't ever worked for me.

In homeopathy it is not good to give Wormwood to children which is what is in the dr clarke protocal. But, dr clarke mentioned that the gren walnut hull tincture can kill everything on its own.

Most doctors just use hospital labs for their tests. Unless your child has had specialized stool tests done by reputable labs, I would not count the negative results AT ALL.

Your child could have a protozoa infection. Many protozoa cause diarrhea.

The following link shows comprehensive stool tests offered by Genova Labs. They may/or may not do pcr (DNA) testing, but I would still trust their results far more than a regular lab. These tests must be ordered by a doctor. Test kits can be ordered by you and your doctor could sign it. These tests are usually covered by your insurance.

https://www.gdx.net/tests/search

My instinct says your child has a serious problem and it doesn't seem like worms. I would not use any parasite cleanse.

It would be great if you can get a proper diagnosis. Children and animals are more readily treated for parasites than adults.

I wanted to buy barefoot's dewormer for my kid but it cannot be shipped internationally. So i sent him an email and this is what he replied: pure oregano oil and dilute with olive oil as 15:1 and give drops, either in his drink or mixed with food. Their p/w formula is mild at 1 dropper dose (their adult dose is 1 tablespoon). They also have a kind of spray or air freshen formula to be used in the room for the night, you should check. No Wormwood , that is only for adult use. The other safe herb is olive leaf, which is 7 capsules daily for prevention and 21 per day for treatment, (not sure which capsules he meant here).
I have read everywhere that their adult forumlas are too mild. But the kid's formulas might be good to try. Or the mentioned oil and olive leaf. About olive leaf and the treatment you can read dr morton walker's book about it.

In an earlier post I suggested comprehensive stool tests. After considering your child's symptoms again, the problem may not be parasites at all.

There is another forum which may be more helpful to you. Try reposting in the "Candida and Gut Dysbiosis" forum. I'm not saying your child has candida, but he does seem to have a gut dysbiosis.

I feel certain you would get more help from this group of posters.

Following the other answers, i wouldlike to add that olive leaf works with many types of pathogens, not only worms. Bacteria, yeast etc. It has no side effects. Deworming your child with herbs, following the recommendations of tested herbs (the guy who replied used this formula for his kids until the age of 12) will not cause any harm. Deworming is also detoxing, i think. It is certainly really helpful to check other forums as well. Although i have searched a lot in many forums about deworming kids and i got lots of vague and contradicting info. So i prefer to rely on tested formulas. Also i don't know how is his diet. A good and balanced diet is really fundamental in order to prevent a lot of health issues. For example children have developing digestive systems and therefore candies, Sugar and processed foods should be completely avoided. It should be all organic and freshly prepared with variety. Also despite the common belief that fat is bad, unsaturaed fat is very essential to developing children. Grassfed butter, olive oil are very good, these help with their intestinal lining. I use ghee, clarified butter which is easier to digest. I put some on warm meals and porridge as well. Same goes for bone broth, meat broth, and as little gluten and white flour as possible. I always use the whole versions, but mostly gluten free. Milk with full fat as well as yoghurt (only organic, because with non organic the animals are fed with gmo crops, so you get a load of glyphosate in your meal!). And nothing processed! Also, a lot of fruit and fruit juices can cause more diarrhea or loose stools. But teeth grinding and bed wetting are typical parasite infected symptoms. In the meanzime you can try to give him some liquid probiotics mixed in water. It has no taste so they cannot protest :) I hope your son will get well soon!