Sounds to me like he is too chilly then, can you do something to raise the ambient temps? What the thermostat is set at and what the temp is in the enclosure are often two different numbers entirely. I would bet if you get your heat to proper levels, he'll eat and until then it might be better he's skipping out or he wouldn't digest well anyways. I'd back off feeding to every 10 days and wouldn't offer anything smaller than a rat pup, moving up to weans quickly. You can get a decent temp gun for about $20-25, I always have a couple on hand to test off each other.