This is the problem with a general topic called "parasites". Many people suffering from many different things, meaning most people needing Prazi (or indeed Ivermectin) will not have "morgellons", rather a multitude of other fluke/tapeworm infestations therefore requiring more normal dosages.
Seizures from prazi are probably due to things like neurocysticercosis of the brain (so indeed should go easy at first if this is suspected), and nausea is pretty normal due to the bitter taste.