Originally Posted by tenderhearts:
she claims she never see's this behaviour even when he plays with other friends kids.
Have you asked her the age group of her friends kids?
I have had a little guy whose mom told the same tale only to find that the other kids were 6+. The playmates were forced to play "yield to the baby" all the time. You know what behavior issue that nets.
In your shoes I'd try the old standard "less sugar/starch, extra servings of proteins, extra outside physical activity, extra sleep" to rule them all out. They are always a great starting place.
Good luck, hope it resolves quickly.