Welcome To BYC
How old is your hen?
When was her last egg?
You are finding more birds that are acting "weird", can you please post photos of them and the poop?
Treating for Coccidiosis shouldn't hurt anything, but if you have an established flock that is older, then investigating further is a good idea. Think if you've added new bedding recently, if they have all been exposed to some type of toxin (oil spills, compost, weed killers, etc.). Have you opened a new bag of feed - any moldy feed, is the date good on the bag?
Check for lice/mites.
Have you added any new birds recently?
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.