My so is 21 months old, he is not able to say a single word.few days before he was trying to say few words of any name like (daddy -daa) but again he stop saying those words also he is just pointing fingers whatever he wants.we told this to out doctor he suggested us to give 'COS3' 5ml once in a day.(doc said it may be speech delay). Is it ok to give cos3 to him ?isn't it too early (he's not 2y old ).