Poop that is not normal (be it wet and squishy or small and hard or covered in mucus) is never good.
A chinchilla's poop is one of the first signs of good health and/or bad health.
If it has a foul odor to it, get him to a vet NOW and have the vet check him for Giardia. You might want to check out the article on Giardia at:
http://www.geocities.com/jobernstein1949/I'm not a vet and I can only tell you what I would do, or have done under the same circumstances. I have been a breeder for many years and have had between 100 to 200 chins most of the time.
If you are seeing little or no poop, it sounds like he is stopped up ... OR ... his system is shutting down.
Best bet is see the vet.
In the meantime, if the cranberry juice does not work, the raisins do not work, mini shredded wheats do not work ... last ditch effort is give him an almond.
Normally you will never hear me say let a chin have a nut of anykind, but, when the digestive system clogs up or stops, your chin is headed for big trouble fast.
A chin's poop should always be firm, moist and oval shaped. If it becomes small and/or hard, he has a problem and is probably already dehydrated! If it is wet and squishy, he has a problem and is or soon will become dehydrated. If is is covered or partially covered in mucous and/or has a foul odor, he's in big trouble!
Again ...
normally, I will not even hint that you should put your chin in water,
but ...
IF the fur is matted on his bum, more than likely he started with diarrhea, it dried and is blocking the rectum opening. If the fur is still matted and dirty ... run a small amount (about 2 or 3 inches) of warm water in the bathroom sink. Place your chin in the sink and clean his little bum by swishing the water back and forth across the area, dissolving the matted fur and cleaning it.
Do not get him any more wet than is absolutely necessary. Dry him with a clean towel and paper towels (paper absorbs more water and absorbs it faster). Set your hair dryer on low blow volume and low heat ... dry the fur by holding the dryer about 8 to 12 inches away from his body and quickly moving it back and forth over the wet area ... do NOT hold the dryer still in one place ... the heat from the dryer will over heat the chin and/or can burn it's sensitive skin! Make sure he is completely dry before putting him back in his cage. You do not want him to get chilled! Note: If the bum looks a little red or raw, put some triple antibiotic ointment on it.
IF the matted fur is what has been blocking his normal flow of poop, he should cut loose with a bunch of them. You can gently rub his tummy in a downward motion to help get things going.
IF he does not start pooping very soon, then give him another almond and get him to the vet a.s.a.p. Once the digestive tract shuts down and chin can 'go down' (die) quickly.
Remember: I'm not a vet and I can only tell you what I would do, or have done under the same circumstances. I have been a breeder for many years, done many hours of research over the years and have had between 100 to 200 chins most of the time. What you do is your decision. Regardless of what happens, I think I would have a vet check your little one out to be on the safe side.
Keep us posted!
Jo Ann