This is unusual in a child of this age.He may have difficulty in swallowing especially if he has a throat infection or tonsillitis. Another cause is reflux but he would have been doing this since he was much younge if this was the cause. Another cause is copying an adult. Your son may have seen his grandpa or someone in the family spitting a lot and he is now copying this behaviour. The best thing is to make sure thar he does not have a throat or tonsil infection first.
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