My son who is 4 years old suddenly pick up this habit of blinking eyes(not the normal way of blinking eyes & with the muscle underneath folding as well) on last Saturday. He is not just blinking once a while but quite frequently with both eyes. He will not do it when you stare at him but when you not checking on him, he will happily & comfortably blinking his eyes. I ask him whether any problem with his eyes, he said no & don't hv to see doctor. I hv use all sorts of ways trying to stop him from this habit but he still do it even though he said he will stop doing it. What should I do? Any doctor/specialist recommended to treat this? Thanks for your advice.