I would get an all flock/flock raiser feed and provide that free choice.When I fill there feeder with the scratch grains they all go running and the New Hampshire pecks at their feet but I noticed she sometimes pecks them in their leg so that might be the reason why they are having those black spots.This is the food I feed them - View attachment 2450401
Their droppings-
Pictures of all of them-
View attachment 2450425View attachment 2450426View attachment 2450434
Bloody stool- That was from last night/Cleaning their coop today.
View attachment 2450435
Use the scratch grains as a treat to scatter and call them in at night or when you need to put them up.
Depending on the size of your feeder, you may need to add another one if the NH is keeping them away from the food. Food aggression could be part of your problem if they are not getting the right diet.
See if by providing a balanced diet for them resolves most of your problems. Keep watch on those sore areas of the legs to make sure they are healing o.k. If you feel those sores need to be addressed, I would either apply Pine Tar or Blu Kote to those places.
The poop does look like intestinal shedding, but if it's consistent, getting a fecal float is a good idea, if not possible then consider deworming and treating for Coccidiosis since the birds seem to be lacking in nutrition.