There are skin tests done by allergists to test for sensitivity to mold(s). An adverse reaction to mold is a type of allergy, just like a food or pet allergy --- they may just differ in symptoms and severity. One way to start figuring things out is if you could stay with a friend a few days, don't change other things in your life like food and pets, then see if you feel any better. Be sure to stay somewhere there is no or much less potential mold. Be sure to wash all, all, of your clothing when you arrive at the new location. If it is a mold problem and you bring stuff from the mold contaminated location into your new environment, then it will be difficult to pinpoint the problem. Molds release toxins into the air which get on all surfaces. There are several ways to test for mold - there are store bought mold kits, you can take a sample yourself and send it to a lab that specializes in mold/fungal testing, or hire a professional environmentalist to test. There are benefits and drawbacks to each. My preference is taking the sample myself and sending it to a lab.