Just do not doctor with drugs or remedies without diagnosis. Can do far more harm and not helpful. One bird ill without any others affected means: separate her with feed and water available, and unlikely others are going to be sick when they have been a healthy flock. Things happen to systems, and more often just one bird is involved. But DO watch for symptoms in your others--
Are your girls laying? Sometimes a soft shelled egg will cause misery, until it is passed along (a rubbery "shell") And it may take several days, then if you find it, (usually the contents are eaten by other pullets, but the rubbery "shell" will be found--under the roost or on the floor of your coop). Often the pullet will walk, Penguin-like while trying to pass a shoft shell egg, but not always. If thisis her problem, and she passes the egg, then she will feel just fine until the next one, if also without a hard shell.
Are you feeding Oyster Shell, free choice (don't mix it with their feed) and Grit, also free choice, for good gizzard griding of grain and other hard feeds?
Both young birds and old ones are the ones likely to have Soft Shell problems.
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Not coccidiosis--would be more than one bird affected--blood in poop--and while we do not know where you live, out on fresh green grass is where the cocci would be available. (I feed Medicated.Starter feed to my chicks--a light dose of Amprolium that will develop immunity to cocci over a period of a month or 2 , and is not a "medication" that can affect eggs or Organic preference.
One bird not in good shape, means separate her until diagnosed--then there may be treatment? A "sick" bird should not be wormed (and all birds would show symptoms, if worms are a problem). And wrong medication can be miserable for the pullet and even cause death.
If you can describe more symptoms, it might be helpful. Droppings? color and texture? Good luck.
