First, no worries about the coccidiosis medicine being absorbed. As long as she drinks, it's getting into her system.
Can you determine if her crop feels hard and lumpy or soft and squishy? A full crop prevents a chick from being hungry, so it's important to empty it.
If it's lumpy, you may need to give her a teaspoon of oil, coconut oil in its solid form is least messy and safest, and then gently massage the crop in a circular, upward motion until you feel the crop empty. You may need to repeat the oil and massage a time or two.
Can you see what her poop looks like? If it's whiteish, you may need to treat with an anti-yeast medicine such as miconazole or Nystatin, the latter you may get a prescription for from your vet. The miconazole can be found at the pharmacy in the women's hygiene products. A quarter inch of the miconazole cream twice a day for a week will treat the yeast infection. Give her probiotics as you treat to help restore a good flora in the crop. Hold off on vitamins until after the coccidiosis treatment is finished.