My DS is 16 months and up and walking, he is and always has been a very good eater and loves his food. The last week he has started having a complete fit if we try to put him in his high hair at dinner time. He just goes mental with full river dance legs and screaming and tears the works. He doesn't seem to have a problem with it at breakfast time though. He will eat if he is sitting on one of our laps, but I really don't want to get into that habit. What on earth is going on?