I think this boys life is probably permanently ruined.
That is a side effect, sometimes, of Ritalin. Whether it directly stunts growth, or simply suppresses some kids' appetite so severely as to reduce growth (as do the related amphetamines), is a question I can't answer.
However, thank God, that didn't happen to me. I ended up normal height for my family. Possibly this was because I was taken off Ritalin in the summers. As I recall, I did more than my share of growing during that time of year.