I have 6 hens, one of them a leghorn is a bit sick looking for the past month. She has her beak slightly open at all times, her breathing is heavy, almost wheezy, she makes a noise like a cough or a sneeze. I thought it was gape and treated her and the others just in case but she is still the same. I got her some vitamins, but no change.

Also the hens are 7 months old now and have not started to lay yet. It seems like they are never going to lay.

UPDATE: 2 leghorns have started to lay.

(See photo below)