Hi there ~
I understand your concerns. You son has become dependent on marijuana to the point where he has loss of patience, focus and is unable to study. I believe that he would benefit from consulting a doctor and ultimately getting him to a rehabilitation
center for drug abuse
would be hugely beneficial to him. I hope you do so as soon as possible. Wishing your son the best in recovery.
I hope this helps. Take care of yourself and have a lovely day!