It's hard to guess which strain. I was looking for parkenson for my father, he had Parkenson. Many articles advised more sative strains, and it turned out that indica was just right for him. In the case of the guy, I also think you need to pick up. What will suit him, for his body and specifically his problem. Everything is individual with the treatment of such problems. 

I wish you to find the answer as soon as possible! 

Good health and good mood!