Sorry you are having a rough time of it. I get that way with my almost 7 year old daughter. Hers isn't negativity though, it's constantly arguing. Have you read the book "Kids are worth it"? It's excellent. Also Love and Logic books by Cline/Faye are good for their age. What about a reward system that could be faded out eventually? Maybe a jar on the table that you'd drop a dime into every time you caught him being more positive, and conversely, remove a dime when you see negativity. Feel free to cry on my shouldre any time. I am right there with ya!