Last fall I got three young hens all of which have just started laying in the last month or two. Everything seemed to be going well and each one would lay every one or two days. All three lay a different color egg so it's easy to tell who's doing what. But in the last week two of them suddenly stopped. I thought it was weird but wasn't too worried until this morning when I found two eggs from the same chicken in the nest box. One was broken and the other was intact but very small and broke as soon as I picked it up. She seems fine, but I'm wondering, is this similar to internal laying? Should I be concerned? My husband was reading that oyster shell can cause issues such as this and they have, until today, been getting oyster shell. Can oyster shell cause laying problems? FYI - this particular hen just started laying a few weeks ago. Anything else cause this sort of issue? Thoughts and/or suggestions? Thanks!