Welcome. There are medications to alleviate some of the physical and mental symptoms. What medications is he on and what are they for? There is a vitamin thread at the top of the page that you could take a look at and start him on, if he isn't already. Hopefully he will improve well in the coming months.
For now, he should be resting his mind and very minimal exercise, if he can do any at all, start with five minutes walking if necessary.
Did his primary refer him to any other doctors?
Others will be along with guidance.