Coils but doesn't eat?

So I've never had problems with my male before, but suddenly he is having problems with actually eating his meal. Last week, he took his food right away like usually, but then I found the rat still in the cage in the morning. I took a closer look at him, and could see he wasn't as vibrant and his eyes were a bit cloudy (he is albino), so I figured he was shedding. Yesterday, I found the shed in his cage, so I fed him again. He took the meal right away again, then I came back an hour later and it was still there, so I did a quick heat up with a blow drier, and he took it again and coiled it, came back 15 minutes later he still didn't eat it, so I shook it and he coiled around it again... then I tried once more last night and he took it again, and I left it overnight only to find the rat still in there. He appears to be very hungry as usual, strikes and coils right away, so I don't know what the problem is. Any suggestions? I was going to try a smaller meal next time, even though they are a bit small for him already. I figure he just can't seem to find how to actually eat it for some reason...

Edit: he is about 400g, give or take a bit, and the hot side is 94-ish, cold side is 77 or so, humidity is in 60s, low 70s

Make the rat much hotter, maybe it's not completely thawed in the middle, but is thawed on the outside?

Or else maybe the rat is old. Has it been in your freezer awhile?