The bugs on her may be lice or mites. What is your location? Permethrin can be used to treat for lice or mites every 7-10 days at least twice. Ivermectin is another product that can treat them.
Pictures of her eyes may help. Are her pupils round and is the eye color normal? Your hen sounds like she may be very sick. What do her droppings look like? Have you added any new birds to the flock recently? Could she be dehydrated? I would offer water to her beak, and if you have electrolytes or Poultry NutriDrench that would be better. Has she eaten any food today? Was she vaccinated for Mareks disease? I would keep her in a dog crate or basket with food and water near her for observation.