Okay, so let's round that up to 1.6 kg. If she were mine I would give her one 250 mg capsule twice a day. It's a little more than the 125 mg/kg amout, but I think there are some formularies that say as much as 150 mg/kg can be given.
Ah, yeah, selling something like that out of a store is illegal. Not sure how the online places get away with it. Enrofloxacin is prescription only, but the pigeon and game bird websites have found a way around the law, that or the FDA doesn't have the manpower to deal with them.
The fish mox will be fine. Enrofloxacin injectable is what you should get, and it can be given orally. Fear not, giving injections is easier than tube feeding, so I am 100% sure you'll have no trouble. :D
Since her crop is slow to empty, I would try to find injectable Baytril. In the meantime, you could try some oral amoxicillin. Dose is 56 mg per pound orally twice a day.
I'm going through the exact same thing right now with a turkey hen. Her crop gets so full that food and liquid pour out when she puts her head down. :thShe's also doing that weird head and neck thing. I started her on Baytril, metronidazole, Valbazen, and Corid. Today I am going to add Nystatin...