We have eight RIR hens that will be 3 years old in May. For the last couple of months egg production is erratic and decreased. At first we thought molting, but then we noticed 3 then 4 of the hens backsides are pretty red and look swollen. Is this normal or something we need to be concerned about. They have been picking at each others feathers so we increased their protein and oyster shell in their feed.