You need to surgically remove the kernals before you leave or they'll be a lot worse, when you return. This is a staph infection and what you're doing will not cure it.
I have a Lavender English Orpington hen that is always the last one out every day. She enjoys having the coop to herself. She comes out, when she's good and ready.
I 've ordered twice from Daniel, both eggs and grow outs. His animals are top notch. A little difficult with communication, as he speaks broken English, but his birds are top quality. You get what you pay for.
I like dosing with terramycin scours tablets(which is basically the same thing) 1/day 250 mg. for 4 days. It's very hard to get right now because it 's made in China and the supply chain is broken. It's not available in the entire TS chain.
Good luck with your bird. I lost my Sally (English...