It is not the gas that's making your stools float but is more likely too much fat/oils. This is a maladsorbtion problem called sprue. parasites are one of the causes of maladsorbtion but there are others you can see by searching for 'maladsorbtion syndrome'. There are two main types of sprue - Tropical sprue seems to be caused by parasites, mostly protozoa. Non-Tropical sprue is more common in temperate climates and many people are genetically predisposed to develop gluten sensitivities, Celiac Disease/Sprue and non-celiac sprue.
For medical options see the Parasite: Drugs Forum and for protozoan parasites see the Parasite: Protozoa Forum.
It is not a good idea to stop using the parasite herbs until you have compleated a course of treatment such as the H. Clark 18 day program or her shorter program using the herbs and a Zapper.