Corn Snake no longer eating.

[Sapesko]

My Rootbeer corn is about five and a half yrs, and about six weeks ago he stopped taking food, which he's never done before. I moved into a new place about 4 months ago, but he had been eating before. I had been feeding him thawed frozen mice but when he stopped I tried a live one, which he also ignored. He's pooped twice since he stopped eating, which surprised me. The first time was about two weeks ago when I had him outside on the grass, and the second time was today in my bedroom - I was surprised both that he wouldn't in his tank and that he had to at all, especially the second time - it was almost entirely liquid. He seems totally active and healthy, but I'm starting to get worried. Any thoughts?