[TabithaA]

I have a 4-year old son with whom I am having a very difficult time trying to discipline. Anytime I exert my authority, he resorts to kicking, screaming, biting, pinching, throwing things. For example, tonight I told him to start picking up his toys in his room. Before I had finished the sentence, he started screaming that he didn't want to. Then, he moved onto the fake crying saying it would make him sick (very dramatic, btw). I picked him up and he started the arm flailing and leg kicking thing, while screaming and crying. I told him, that he had to clean his room and that I would help him.
I told him to put his toys into his toybox. And I started picking up his toys. He started throwing toys at me. I firmly told him that he is not to throw toys at mommy, that it could hurt mommy. He threw some more, so I told him every toy he throws gets taken away and he can't play with it. Didn't phase him one bit...he actually thought it was funny and would throw a toy and say "Take it away, Mommy"
I was getting more and more frustrated, so I took a break, shut his door and walked into my room. He started kicking the door to his room and throwing some of his toys at the wall. After he had quieted down some I went back into his room, and the "game" started again. He kept laughing at my attempts to make him listen. When I told him he had to sit on his bed until I told him he could get up, he would run and jump on the bed and then would get off and do it again.
At one point he got so angry he just started hitting me over and over again, so I had to physically restrain him in my arms til he calmed down.
I broke down and started crying because I didn't know what else to do. I've read books, and have tried every discipline method. They all seem to work in the beginning, until he thinks it's a game and doesn't care anymore whether he's in trouble or not. I'm at my wit's end.
I've had suggestions to remove certain foods from his diet, such as wheat and sugar. I don't give him a lot of sugar to begin with, but maybe what I do give him is too much for him. Of course, I'm not sure what types of candies/snacks he gets at daycare, though I'll ask tomorrow. Has anyone had any form of sucess with dietary changes and behavorial problems?