My Son Is 8+ Years. He Is Autistic. He Is

my son is 8+ years. he is autistic. he is taking sizodon syp. 60 ml since last 8 months after consultation of doctor. his daily dose is 10 drops twice in a day. Since last 5 days we have not given him the medicine as its not available in the market. after the discontinuation of the medicine, he has become more hyper, less attentive, speech has also deteriorated, understanding level also gone down... please guide me. I consulted a psychiatrist doctor at apollo hospital and got the above medicine prescribed. while taking that medicine he was behaving properly, was more attentive, calm. please help me.