My baby corn snake won't eat?

I got a corn snake a few weeks ago, and the guy at the shop told me to feed him the following day, as that was when he was due a feed. However, he didn't seem interested at all, and was more intent on getting out of the box i put him in. I tried again two days later, to no success, and then three days later. I then tried putting him in the box for longer, and placing something across the lid so he couldn't feel scared and exposed. He simply used the fact i couldn't see him to get out of the box, and i caught him just in time. I then put him in a box, with holes poked in the lid, and left him overnight, and he still wouldn't eat. I've tried this twice more since then. It's been three weeks since i got him, and he still won't eat. At first i thought it was the stress of moving, but he's settled in fine, and doesn't even act scared of me when i put my hand in to say hi, he slithers on volunarily. His eyes and nose are clear, and he's quite active, though not as active as he was when i first got him. I'm really worried that there is something seriously wrong with him, he won't even go near the pinkie, and recoils when i put his head near one so he can stiff it.