My Chinchilla Pickle kept me up all night by making a scared sounding screech?
Actually, yes he could have had a bad dream. My oldest (Phoebe by the way) always barks while she's sleeping in her tube. There's nothing wrong, and when I check, she's fast asleep. Just make sure there was nothing in the area to scare him, then don't worry too much about it. Chinchillas reach maturity around 8 months of age, but can reach it earlier. He might get a little...excited at this time. You could always google "cuddle buddy", which is a fleece toy (stuffed with more fleece) so he can do his business and have something to snuggle with since he is alone. You can make them yourself as long as it's fleece and stuffed with fleece (they can't have that filler stuff), or you can buy it. Oh and about the lack of calcium thing, that wouldn't cause him to make a frightened noise, but if you want to know if he has enough, check his teeth. If they are a dark yellow or orangy colour, then he is getting lots of calcium. You don't need those blocks, you can buy dried rose hips. They are high in calcium and also a healthy treat they can have every day.