Your chick is constipated, and it can be life threatening. It's also very painful, so you need to act immediately.
Mineral oil is the best thing to get into your chick since it isn't absorbed and will target the stoppage. Every chicken first aid kit should have this item.
If you chick is drinking, you might be able to trick it into taking a big sip of the mineral oil by holding a small container of it under its beak. If that won't work, you'll need to get an eye dropper and squeeze some into the side of its beak. You might also squirt some up into its vent, too.
