She is about 9 months old and has oyster shell, egg shell, chick grit. They are show chickens so she is on 16% protein pellets and eats bird seeds. Also I got her a few days ago and she had worms so she is on wormer medice could that be the cause? Also the
other hen is on the same medice but lays fine. @Eggcessive
I would just watch her eggs for awhile to see if it continues. Some chickens won't always eat the extra oyster shell, but they will readily take crushed egg shells. She could have some problem absorbing calcium, or a problem with her she'll gland. It may work out or not.