I'd take it slow trying to get the crust off as you really don't want to tear the skin inside the vent because it would be hard to keep clean and heal. Long epsom salt soaks might help. You can also feed her some antifungal cream or use acidified copper sulfate in the water for a few days in case the fungal infection has moved farther up her tract than you can reach.
Do you have photos of her vent and the crust?
The vet prescribed Clavamox for bacterial infection, was a culture ran?
White crusty material, does it smell like yeast? Did this hen have a prolapse? Is her crop emptying?
I'd apply coconut oil or mineral oil to the crust, it should help eventually loosen the material. Daily soaks in an epsom salts bath may help as well, as long as she's not lethargic.
They ran a lot of tests. We were there for 5 hours. Vet paperwork said slight bacterial infection. Not a lot of yeast. That was on the 24th. I’m afraid the antibiotic killed all the good bacteria and made the yeast worse.
No prolapse. I was very gentle trying to get the crust off. I’ve ordered the Q tips and coconut oil. I’ll apply that when it comes this morning. I know it was uncomfortable for her. But she did poop right away when I got a big glob out.
What kind of topical can I safely apply inside the vent to prevent infection?
I started acidified copper sulfate water Friday afternoon. I’ll continue through Monday. She gets two pea sized miconazole globs a day and I clean, apply the cream every day. The discharge has slowed way down. It does smell bad.
I have another thread with some more detail on those issues. https://www.backyardchickens.com/threads/is-this-vent-gleet-or-something-else-looks-a-little-like-some-other-pics-i’ve-seen-here-but-not-completely.1560291/page-3#post-26510861
Thanks
UPDATE
Went out this morning, crop is good. She no longer burps etc when I massage it like she had been a few days ago. Behind is a little irritated and just a little discharge.
At almost $1000 dollars spent on vet, meds and all the stuff I’ve read about on forums like this and Google searches and had overnighted to have on hand, I’m hoping to bring her through it. No lethargy, eating and drinking. She loves the late night mash she gets while I’m cleaning her vent. Seems to be a little
Too used to it. Lol
My wife thinks I’m crazy for going to these lengths. Farm friend down the road said cull and move on. Perhaps I am. Perhaps I’m not. Don’t care at this point.