What Is The Treatment For Speech Delay?

Hello Doctor, My son is 28 months old and having speech delay. He started saying words and responds well from his 8 months onwards, but became less interactive after i start giving cow s milk from 1 year. He has started beating when he sees new people. He is shouting and always likes to run and climb stairs. He is uncontrollable sometimes. Please advise what actions i should take inorder to bring him normal. He says 1to10, some alphabets, can hum songs, identifies more than 20 animals, some colors and if he is hungry he points to food, he likes & drinks milk. Please guide.