HELP! Silkie has repeat lice and now dark runny poop

[farmgrl7]

My 4 year old silkie hen gets lice often and I treat her and they go away and come back again. Not right away but they do. I keep an eye on her rump and keep it debris free and she’s usually a clean hen unless she’s broody. Today I was holding her and saw a louse crawl across her face. Scrubbed her butt but now she has dark runny watery poop. Quarantine?! Help?!?

 

[casportpony]

What are you treating the lice with?