Several of my hens have a small hard swelling on their breasts, so much so that their feathers are sticking out away from their bodies. When I felt the lump on one, it was like she had swallowed a rock. The feed store gave me the wrong thing when I went in last, sawdust instead of shavings and like an idiot I used them. I think the girls are maybe eating the stuff and getting impacted. I lost one Saturday and I'm very much afraid these will die too. Please tell me what I need to do for them. I'm moving and all my chicken books are packed away god knows where. Thank you so much for any help!