I hired an inspector to come to my house to take an air sample. They sampled the air in two problem areas of the house and then a sample of air outside and sent it to a lab for analysis. We were only testing for mold, but they could have tested for other things if we had indicated we wanted them done. The cost was a few hundred but for us it was worth having a concrete answer that our house was making us sick. It also helped our doctors to treat us appropriately based on our exposure so the information was truly worth the money. I found the company that tested our air off the following site (I sent the link for TX). Maybe just call a couple and ask for their opinion over the phone.
Indoor Air Quality Association (IAQA)