Not at all unusual behavior for any of the ratsnakes, and I have read that baby foxsnakes are especially prone to fall fasting. First, make sure that he has proper temps and a warm spot where he can go after a meal. If all that is already in place and the snake continues to refuse food, you can try enticing him by cutting off the pinky's head and leaving the snake in a small container with the head and body. You might even sqeeze the decapitated head just enough to squeeze some of the brain-goo out the neck. YUM!!! I only suggest these measures this time of year for baby snakes, as robust adults can overwinter just fine with no food at all.
If your snake continues to refuse food after such attempts, put it in a cooler area, preferably dark, for several weeks. When you bring it back up to room temps and them turn on its heat source (not all at once...room temps for a day or two and then additional heat)...The snake will often "cycle back up" and start eating again. My fall fasters always have.
Several of my larger ratsnakes are currently on their annual hunger strike. If they keep it up, they wind up in the basement for awhile. I only really worry about the little ones, as they do not always have the fat reserves to make it through the winter. I do have a pretty small garter that went three months without eating last winter. After the above procedure, he came out eating like a champ. He's fasting again also. Duffy