anytime you are in a situation where the buyer is requesting a mold inspection/testing be done and they tell you they have a medical predisposition with regards to mold you should direct them to consult an allergist/doctor and an industrial hygenist.

You really should only be attempting to identify if there is visible mold or residual mold spores present. After that a remediator , a IHyg, or allergist/doctor should be recommended.