We have a small (35 birds) flock of red sussex and sex-sal link laying hens that have been free ranging since April when the grass came in. Currently they also get a feed ration of chopped oats and rye. In the last few weeks we have noticed a few of the hens having some diarrhea, or poo that sticks to their feathers anyway, and then upon close inspections their vents appear to be pussy or oozy, the colour is a light tan. Any ideas about what this might be?! Should we worried about all the birds?