How Can We Deal With Our Autistic Child?

Dear sir my only son is diagnosed with Autism who is now 7yr old. he looks as normal kid but he cannot speak. though he utter few letter it s meaning less. he always engaged in some activity no diversion he can tolerate. he is poor in attention. he cries but cannot express his need/pain. he cannot fulfill his basic needs. i am lot worried about his development and future. the pain we feel when he cries and we fail to know why he is crying. pl. leave your valuable advise.