Do you have photos of your hen and her poop?
What did you deworm her with (product and dose)?
I'd work on hydration, see if she will eat some wet soupy food. I'd be inclined to give her extra calcium for a few days, you can find Calcium Citrate with D3 in the vitamin aisle of stores like Walmart, CVS, etc. Give 1 tablet daily, just pull down on her wattles, pop the tablet into the beak and let her swallow.
Can you feel inside the vent for an egg? You mention her abdomen is swollen and large - is that below the vent between her legs? Does is feel like fluid? Ascites (Fluid) can often accompany reproductive disorders.
Corid will treat Coccidiosis, do you feel that is an issue for your flock?
Liquid Corid dose is 2tsp or Powdered Corid Dose is 1 1/2tsp per gallon of water given for 5-7 days as the only source of drinking water.
Do not add any extra vitamins/electrolytes that contain B1(Thiamine) to food or water during the course of treatment.