Have you left water bowls around for him? I'm sure if he has water available he will be able to survive for several months. There have certainly been stories on here of snakes turning up after even as long as 7 months. Try sprinkling some flour around the edges of your rooms as that might give you an idea of where he is. Have you tried a bottle trap? If you search on here you will find how to make one. I'm no good at posting links. Another thing to consider is if he is due to shed. If he has gone in blue he will be holed up somewhere so you will be unlikely to find him or see any tracks until he has shed. The good thing is he will probably be hungry afterwards.