Hello and congrats on your new chilla.
Do you have any idea how old your chilla is? Maybe he is just a youngster and is taking his time to adjust and learn about his surroundings.
Patience is key. It will take more than a few days, more like a few weeks, for him to know you and trust you.
We always start out with just some scritching under their chin or on their head.
And we make sure they have lots of quiet time during the day to sleep.
1) make sure he has fresh water daily, some people even use bottled spring water.
2) a good handful of hay daily, timothy is great.
3) start with the same chinchilla pellets that he was getting, and make sure they are high quality. If not, then wait and change him over slowly later on.
4) limit treats until he adjusts and settles down.
5) for his bath bowl, use real chinchilla bath dust
, NOT sand.
6) cage location should not be near a heat/cooling vent, not in sun, not near TV/stereo etc.
8) I wouldn't add another chinchilla unless it is in a separate cage, even then, let him get to know and love you first.
9) many chillas stop eating when their teeth are too long or they have a bad tooth alignment called "malocclusion". Vet care will be required.
10) it is SUPER important to check his droppings daily, they need to be slightly oval, moist, and not long and thin.
Lots of suggestions here, and I don't want to overwhelm you, but I've had chillas for a very long time and rescued dozens.
It may be helpful to search out a good vet just in case you ever need it.