Please answer all the questions in the emergency sticky at the top of this section so folks can best help you help your hen. Include anything/everything that might give clues. Include egg laying situation for her - age, when last egg known to be from her etc, exactly what her diet is, etc. When/if wormed, condition of everyone else etc.
Get her in a comfy place (large dog carrier with deep layer of clean pine shavings in a room where no one will bother her except those she trusts, where there is no stress and it's not too hot or too cold, plenty of food and water right near her, and note eating, drinking, poop conditons.
I have to head to work but hopefully your info will come along soon and your sick hen can be soon helped.
JJ