have to pay several thousands for assessment first (except for Po Leung Kuk)
have separate courses for ADHD and read/write problems
Medically, there are medicines for ADHD, consult your family doctor to refer you to a psychologist. One visit may cost over 1k
Consider switching to a less stressful school, else he will not be happy, may lose interest studying if he is always the last in the class and may be excluded by schoolmates.
A friend's son is an ADHD trouble maker at school. The parents refused to take medicine, only use behavioural and social classes. No one likes him in school and the teachers scold him every day. No interest to study anymore.