My 3.5 yr old son only speaks words like Mama Dada Pa and he had started uttering Dada when he was just 6 month old.....now at 3.5 he is not able to speak properly even he understands things and recognises them......he can play games on mobiles and easily play music......but problem is that he doesn't even speak properly words and whatever he says alone is in his own languages.....pls help what to do