Hi, the other day my ducking who is about 5 weeks popped her air sac by a nasty fall due to my husband. (She is ok now, and it was not his fault she jumped out of his hands) She had the bubble on the side of her neck for about 3 days and it went away on its own, so we thought we were in the clear. But today I was loving on her and where the bubble used to be it is now an oval lump under her skin. I have been reading everywhere and I do not know if it is part of her crop or if I should be concerned. she does not seem to be in any pain when I touch it and is active like normal, she also may be a tad bit overweight, but I am not entirely sure how to tell, she has access to food and water 24/7.