Hi! Our 3 year old Rhode Island Red has been laying 3 eggs or so a week for the past few months. Lately though, her eggs are often laid with either a very thin or rubbery shell or sometimes with no shell at all. (The rest of the flock is laying well with no problems). We feed organic layer pellets with free choice oyster shell on the side. Anything I can do to help our RIR with her problematic eggs?