Hard potty of 2 years old. Help me!

Hi My son is 2 years old. He has been suffering from developmental delay and having behivioural issue. He passes every day hard stool. Even he takes proper liquid  still very hard stool. It takes 15-20 minutes to pass stool. Till than he runs here and there sit stand many times . Also He can't sleep better in night. He keeps tossing in night. He sleeps late night and takes arround 1-1.5 hour for us to get him sleep. He sometimes put is cheek on my stomach on My legs turn here and there. Apart of this he rubs his nose put finger inside nostrill keep rubbing eyes too without any illness. Even he rubs his nose on pillow bedsheets. And many times he wakeup from sleep because of this itching in nose. Suggest some medicine for soft stool or constipation and also for nose allergy and sleep issue. I have listened melanotin but don't know dose and brand help me