I've been feeding my chickies starter crumbles - nothing else. They all have developed large crops - I'd say large marble sized. They are noticeable and odd looking. My girlfriend told me to give them a little sandy grit from outside. They gobbled it up, but have not shown any difference in the size of their crops. I read up on swollen/impacted crops on the chick emergency thread, but it seems odd that all the chicks would have it at the same time. They are on pine shavings having been on paper towels their first week. Should I give oil, yogurt? What's going on here? Thanks!