There are several illnesses that could cause a head tilt in snakes, and only an in-person exam by a qualified reptile vet can lead to a diagnosis.
Cryptosporidia (but I like your spelling of it
) are single-celled parasites known as protozoa, and are quite nasty little buggers to get rid of. The problem with "crypto" and herps is that it can be a chronically active pathogen with or without clinical signs.
Many difference virii or bacteria could be causing the head tilt, as it's the region of the body affected that is pertinent and not as much the actual pathogen. If you vet friend is suspecting crypto, I imagine that there was other information in your hognose's history that suggests it.
Neurological damage from physical trauma or environmental toxins is also a possibility.
Christina
www.herptiles.net