My brother was a healthy man who was VERY intellectually smart. A few years ago when he was 24, he came back home due to an inability to think, headaches, and problems after eating. He barely drank alcohol, NEVER tried any hardcore drugs, ate VERY healthy (healthy body) and exercised.
He has gone from a quick-thinking, healthy man working for NASA to a sick shell of his former self who is skin and bones from not eating (inability to digest food, headaches and brain fog after eating), who has been bed ridden the last 3 years to sickness.
Has been to MANY doctors and diagnosed with EVERYTHING, given medications to treats those diagnoses but NOTHING works! He is STILL sick and is worse off now than when it first started!
The only diagnosis that makes sense is Autonomic Dysfunction. Doesn't mean that's it, possibility.