I have a hen which appears to choke and gape after taking water. She has been wormed. and so have the others in the flock for Gape worm. The others do not exhibit any signs of worm or anything else. She is generally happy and scratches around like they do. This is ongoing and has been so for about 4 weeks... She appears also to have laboured breathing when resting and when walking her legs are raised up into her chest significantly higher than the others. Does anyone have any ideas what the problem might be?