My four year old son has recently started stuttering even though he was speaking perfectly before now. Should I be concerned? He says things like "Mummy, I I I I I I want the dinosaur" or "May, may, may, maybe we can go to the park". He does it even when he's calm - not excited, just in regular speech and he does it constantly - almost every sentence. I am not sure if this is a stage or not, or even if maybe he's heard someone doing it and is copying their speech. Should I take him to a GP or something?