You go to an allergist and he can determine if you have one of about a half-dozen dangerous molds in your system, he can
test for those specific kinds by doing a culture. If the allergist is clueless as to what those toxins might be, ask him for a referral. Also, you can do an online search for the words "toxic mold, symptoms" and you'll get some websites that list them off, so at least you'll be knowledgeable about them.