Check out yeast/fungal overgrowth, too. Both the overgrowth and the die off when you start using antifungals can create gas byproducts like ethanol and acetaldehyde. Crazy stuff.
More info here:
Y/FO post in the "New to Lyme?" thread:
www.healingwell.com/community/default.aspx?f=30&m=1606610&g=3644275#m3644275-p