If they stop eating they're young it's almost always stress from a new home, to large a home, or improper temps. Get a temp gun, you can find one for $30 on line, they last forever and are probably the most important thing you could buy. With a temp gun you can get an accurate measure of the actual temps your snake is experiencing where other methods only give you a vague ambient air temp. Get an accurate measure of the hot spot and the cool end, aim for a 90 degree hot spot and 82 cool end. You can also bump up the humidity to 65%. I cover most of the tank screen with glad press n seal to keep the humidity from escaping. Keep him in a quiet room with lots of good hides, mine love cereal boxes, they're much tighter and darker than the open half logs. Cover his cage all the way with a towel or something so he feels as secure as possible and leave him alone for two weeks, just go in for cage cleaning and to give him water. After that offer him some food, if he doesn't take f/t try a small live meal, feed him smaller meals than normal. I get a lot of adult females that were sold as horrible feeders and this has worked for me almost every time. Adults with go off feed for the winter and be fine but younger snakes should not be going off feed without a reason yet and will lose to much weight. Make sure his set up is good, leave him be for a bit, and get scale to keep track of his weight and he should come around just fine.