Mixed OCD

22 year boy suffering from intrusive thoughts repetitive behaviour goes his own particular way from the last 10/12 years however he is aware about his problem at present symptoms are increasing day by day. We have tried number of medicines like SSRI and antipsychotic but of no use instead of improvement getting worse with antipsychotic A symptom which make him stuck is few sounds and displays like sound of Running tap water, machine sound, still screen of mobile or TV/computer he gets statue TV now Dr suggested Gamma knife surgery but we don't know what to do please help