Depression 09 yr kid. Be sideeffect!

Hi doctor, Last month my son shunt was revised as he has condition called hydrophelus,post surgery his confidence level has gone down,his pediatrician has diagnosed his condition said he has mask depression and prescribed amitryn 25 mg for 10 days after days 12.5mg for 20 days,currently he is behavior is not at all good. Behavior which we are noticing as follows 1)Attention seeker 2)Interrept 3)Emotional 4)Talks too much 5)Anger issues 6)Jealous of her sister if we praise her. 7)Complaint box 8)Do not get along with friends, often quarrel 9)No interest in studies, watching games and youtube all day 10)Has become negative after surgery and has lost complete confidence,keep asking me again and again why this happened to me Very Good in riddles quiz and maths,Know All the Gamers and Influencers on YouTube, Along with Likes and Subscribers I am scared of giving anti depressent medicine as heis very small,should I start giving him medicine,if yes then till when,will there be sideeffect