| I would make sure the temp are up like 28 - 30 to 24 - 22 cold end, with plenty of water, snakes thermo-regulate there body temp and can only bring there temp up by 2 degrees by like shivering.
A snakes body temp needs to be 30 degrees for them to digest its food and stay active enough to want to eat. Thats why they need a cold spot to keep there temperature from getting high, the only time there temperature is dropped is when there ready for breeding and have not been eating. always use a thermostat with a safety cut of switch. if it still persist then see a vet.
cheers steve. | 
