Welcome to BYC!
I couldn't get mine to vomit! Clever lady! I've actually had to operate on 2x hens with sour crop! Both successful and survived. And, no, I'm not a vet. Some years ago now. I've had chickens for 7 years now. And, no, I didn't put them under and they didn't feel a thing! Thank goodness! Well, no pain, otherwise they would've jumped off my lap or table. They just lay on their backs, blinked at me and let me do it! They trusted me! I was really scared but couldn't afford to take them to the vet so had to do a lot of research. I used Tattoo Cream to deaden the area as advised by a clever Chemist! To my relief, it worked! The hens knew I was trying to help them. Everything was sterilized beforehand. Used long strands of hair from my dog's tail for the internal stitches of the crop so I didn't have to worry about them not dissolving and white thread for the outer. 7-10 days later, I removed the outer stitches and they just went about their business! The operation took quite a few hours! (i.e. From what I can remember!) I was very grateful that I had such patient patients! Lol! Never have had a problem with it since because I've never given them loose grass strands again! It just got entangled in their crop and blocked their ability to digest it. But, I haven't had a problem since! Fortunately, as you may gather, I'm not a squeamish person! I do realise that not everyone would be able to attempt it. But, then again, you won't find me parachuting either! Lol! We're all different! ;-D