How old is this chick? I assume you mean "pullet" as "hen" refers to an adult chicken. Or are you speaking about a grown hen that lays eggs? How old is she? When was the last time she laid?
If this chick is a week old to four weeks old, it may be having crop issues due to lack of grit for its digestion. Sand is necessary for the gizzard in chicks that are being fed grains and food scraps. If you have it indoors, it isn't getting grit unless you are feeding it some sand with its food.
If you look at the vent where the poop comes out, if you see pasting over, you can assume the chick may be constipated. Take some coconut oil and break off tiny bits and stuff it into the beak until you get a good spoon full into the chick. Massage the tiny bulge on the right of its chest to mix the oil into the crop contents. Then you need to clean the feces off the butt and clear the vent so it can poop. Using melted coconut oil and a soft cloth. Do not rub the tissue on the vent or it will inflame and swell.
You will need to wait for a few hours for the oil to work, but it should pass a large turd and start to feel better.
The chick may also be too hot or too cold. How are you keeping it warm? How hot is it where you have the chick? Is the chick getting cool water to drink?
