It may be fungal hard to know.
Scaly Face Mites comes to mind too.
Did the vet take any scrapings to help I.D. what may be going on?
If you are struggling getting meds into her, you may need to swaddle her in a towel to help control her.
For mine, I like to stand up, place them on a table so I can pull them to me with my left arm, I use my body and elbow to "hold" them, that frees up the left hand to control the head. She doesn't have wattles, so you will need to grab the rear section of her beak between your middle finger and thumb, gently squeeze to get her beak open, from there you can get your pointer finger in the beak - pop the pill in with your right hand, immediately let go of her head so she can swallow. I know, sometimes they are very good at spitting out pills.
You can also crush up her dose (make it powder), mix it with just a bit of liverwurst or similar and give it that way.
https://www.backyardchickens.com/ar...er-construction-check-back-for-updates.73335/