The medication is called Trichozole which I'm assuming is another name for Metronidazole. I read your tips and tricks for giving oral meds that you linked in another thread, very helpful stuff.
I came across something interesting in this
article. Do you think feeding oregano will help as much as the article suggests? Anyways I am giving some fresh to them daily, they love it.
While making my order for more Lafeber products on eBay I found this product
and wondered if it could help Mabel with her irritation. I know liquid supplements are typically not recommended but I thought it might be worth a try? A little bit added to her soft food perhaps?
Also going to add a couple of pics of one of the patches she has plucked. (Note that she is wet from her shower, when she is dry you can't see the bald patch without parting the feathers.)