Cecal and/or large roundworms. Hit them with the safeguard liquid goat wormer 1/2cc orally undiluted to each chicken for 5 days straight, 14 days withdrawal after the last dosing. Piperazine wont treat cecal worms. The Rooster Booster takes too long to treat and you wont know if they'll eat...
The final diagnosis at the bottom of the second page pretty much sums it up. She had multiple problems going on besides coccidiosis.
Sorry for your loss.