Snake not eating but using bathroom (please help)

[Zexion~]

So my snake hasn't eaten for a little over a month now (corn) but the past two weeks I've noticed clumped urate and some black crust (?) in the corner of the enclosure the first time I thought I noticed some poop also.

Other than that no major symptoms of anything besides he "sneezes" but he's always done that when I bother him a bit too much.

I don't know what to do and my parents are on the fence about taking him to a vet.