Here’s a basic guide for dosages for antibiotics, though I’ve noticed things that aren’t quite accurate on this website so consulting with a vet is always better. http://www.poultrydvm.com/drugs.php
What feed is she on?
Does she have a calcium supplement like oyster shell?
Have you seen any kind or discharge coming out of her, particularly yellow?
Excessively eating dirt “pica” could be due to a nutrient deficiency or some sort of irritation in her digestive tract like an infection...