Talk to Gastroenterologist on Constipation Followed By Anal Fissure

AoA. My younger brother is on clozapine since more than 10 years. He got severe constipation 2 weeks back and given some emergency treatment; first Glycerine suppositories and than advised to use movcal sachet for relief of constipation. Gen Surgeon advised him to use lignocaine Gel and GTN ointment for 3 weeks considering it a case of Anal fissure. Initially he was having severe pain complaints 3 to 4 times during the day which has reduced reasonably now! His constipation problem has solved but very little liquid amount of stool passes away 4 to 5 times during day apart from regular stool passing activity which is disturbing him a lot. Kindly advise what course of action can be avoided to recover from this problem as this problem is almost 2 weeks old. How this can be stopped? Just to let you know his LFT, Blood CP, Creatinine are o.k.