My Son Is 35 And Just Told Me Has Unintentionally

My son is 35 and just told me has unintentionally lost 25 pounds over 6 months. Has chronic cough,complains of funny smell(Like mold) in nose and perhaps ear. Chronically tired (used to be very active) , muscle and joint pain, hair loss, poor concentration. Symptoms worse at work. Basement full of mold. Past history of asbestas exposure. He is an APRN in practice and a lease on building but at the moment not clear what to do for himself. Yet he has been very good with his patients. Concentration if poor and for him to admit to me he does not feel well is EXTREMELY unusual.He just gave himself a kenelog shot to see if it would help. Not a lot. No substance abuse. As a teen but not since age 22. Totally clean since. He had HSP at 18 months old. Homozygous for MTHFR gene. What type of specialist to begin with?

Thank you