I give grit and oyster shell free choice all the time.Ahh I read an it about possible vitamin deficiency. Would the probiotics and electrolytes you get in the packets help at all? I have been offering a crumble 22% protein with added vitamins and minerals. Will post pic of nutrition label. That does makes sense though how it came on suddenly and that they seem fine otherwise. Let me know what you think of the info in the food I've been giving them. Oh also I offer grit every few days. Should I offer daily or less or how often would you recommend?