Ok here's your issue. 10 pounds is OBESE even for an average full grown female. My girl is only 5 pounds. He is most likely just not hungry. Maybe trying to lose some weight LOL. But there are owners on this site who have had snakes not eat for over 9 months. 3 weeks isn't anything to worry about unless he has loose stool all of the time or he is rapidly losing weight. It's also winter and he might be trying to find a mate.