hi I have a ball python named monty. I was given monty about a year ago and don't know how old he is he's approx 4.5 feet in length and he is housed in a viv 1200 x 450 x450 with a hide each end a good size water bowl he has ceramic heat lamp with a pulse thermostat at about 86 degrees warm end and a light fitting I have recently replaced the bulb to ultra violet (yesterday) it is set up to day and night cooler with no light at night and so on . And he has always been a good feeder but about 3 months ago he slowed down not as active and has gone of his food only feeding occasionally I still offer him food once a week but most of the time to no joy could it be a winter thing or am I doing something wrong please help