Such needy little guys, huh? Poor baby. Have your vet examine him. Perhaps he has something of an incontinence issue. Wolves are exceptionally jumpy and skittish by nature, and an intestinal problem may only exacerbate the situation.
I agree, contacting a wildlife specialist might be in your best interest.
Wolf People is an organization here in North Idaho that tries to educate people on wolves and even allow people to see some of their more stable pack members. They may be a good place to start looking for answers. http://www.wolfpeople.com/wolfstore/help.php?section=contactus&mode=update
I agree, keeping him outside is not ideal. Wolves aren't pets, and they certainly are not outside pets. Anybody who's ever owned one or known somebody who has most likely figured that one out a long time ago. Only people who've never owned an actual, real wolf would be under the mistaken impression that this animal should be tossed outside because he is so easily frightened that it's making messes. I'm glad permits are required to own these animals, for the sake of the poor wolves!
He doesn't have to have been abused to be this way. They are shy and easily frightened, and no amount of socialization will change that (usually). Start with your vet and the links I provided down below, perhaps you can find some answers. Extreme fear can result in spontaneous defecation in canines, so your task is probably to figure out a way to keep sudden noises from making him jump out of his skin.
How is your interaction with him? Are you treating him like a dog or like a wolf? A wolf is happy with a firm, consistent leader. Google NILIF training for a start. Since he is so fearful I think a firm but gentle leader would probably suit him best. Never raise your voice to him, just use calmly-stated commands, or growl them if they need to be repeated. My aunt's wolf's favorite command was "table". It meant to go to his happy little cave i.e. under the end table by the couch!
Perhaps you can get him a crate, just large enough for him to stand fully upright and turn around. Probably an x-large crate since wolves tend to be pretty big. Cover it with a blanket and leave the door open so he can come and go at his leisure. Put it in a "safe" area of the house, like your bedroom. When he has his a more secure place to run to, he may calm down a little. Under the bed is open on two or three sides, depending on whether or not it's in the corner of the bedroom, and he may still feel exposed.
Work on some training with him. While they aren't the best for obedience training, other more practical things like recall, heeling on a leash, and just some general pack bonding time in which you are in clear control should help him relax a little as well, and build some self esteem at the same time. Also, if you haven't already, leash train him and take him for a looong daily walk somewhere nice and quiet. Let him sniff, roll around, run around. Consider a retractable leash and jog with him. A tired wolf, like a dog, is more calm. However, to tire him out you'll have to jog/run him for at absolute minimum one hour per day, preferably two or more. If a bike doesn't terrify him, it may help. :D