Wanted to follow up and thank everyone, especially
@Wyorp Rock , for your help. Onyx has been back to her normal self for a while and today I was able to confirm that she is laying eggs again

. We have 4 hens who lay almost identical eggs, so I weren't sure if she was laying or just hanging out until today when she stood up in the nest box and I pulled out an egg that was still slightly wet

For what it's worth, she and I compromised on the pills. I didn't like measuring out her dose, but she loved the coconut oil pill. I ended up mixing the whole amount in coconut oil and just assumed that some would be lost. She learned within a day to recognized the wax paper I used to hold it and came running up to me for her special treat.