Why would just one hen out of 11 be laying a very soft shell egg? They all have acsess to crushed egg shells free choice. That is all I have ever used for over a year and have had no problems at all. I have noticed for a while egg yolk on some of the eggs. More than once I have had to change out the straw bedding in a nest box because it was wet with yolk. I really thought we had one or more of the girls breaking and eating the egg. But shell was no where to be found. Today I got one that the shell was so thin you could have ran you finger right through it. The shell was very pale nearly white and mine lay brown eggs. I have been getting a pale thin shell from one of the girls for a while but not this paper thin. Is she just not eating the crushed shell?? Or is she sick?? I recently changed from laying crumbles to Flock Raiser which has less calcium. This was done because I have younger pullets that can't eat the laying crumbles yet because of the high calcium.