Young pullet appears to be choking. I gave them some scratch corn for the first time, and she's acting like she's trying very hard to swallow. Keeps putting her head back and swallowing. Some foam is starting to develop in mouth. I'm unable to see anything in mouth or throat. Tried turning her upside down hoping maybe she could vomit it out, but not sure whether technique is correct. Tried rubbing front of body from throat down in an effort to help work the piece down. What to do?