i find that the 3 kids that i have in dc (one 4 yr old is similar) are always better after they run off their energy outside...it's like they have too much energy and they're like wild animals at times... and the winter was so long...i'm finding now we can go outside more, it's better. also i find their behavior tends to be better after meal. i have a grown son who was extremely challenging at 4, and now at 18 he can still challenge, but he is also lovely in other ways... he even says to me he remembers being difficult. if you don't need to keep him, give notice as it can disrupt the harmony you are trying to create with your daycare.... good luck!