Im Writing On Behalf Of A Friend. He Is A

Im writing on behalf of a friend. He is a 58 year old male living in Central Florida. He has had rapidly deteriorating health, beginning about 4 months ago. He has had numerous trips to neurologists, family doctors and none have been able to pinpoint what it wrong with him. It seems clear to me that he needs to have more testing done. Has great insurance, but nobody seems to follow through and find out exactly what is wrong with him. He seems to think that he may have chronic carbon monoxide poisoning due to driving an auto with an exhaust leak in the manifold. My question is, is there a test of some kind that he can request from his neurologist or family doc that can verify or eliminate co as problem. tia for any help