We have a black sex link that lays eggs now that end up with a hole in it the size of the writing pen, one egg had a thin piece of shell hanging from the hole, today's egg had a nice size hole letting the white run out. She is going on three this coming fall. She had been laying eggs without any problem, now this season is different. She is getting oyster shell, grit, layer feed, worms, bugs. All hens have free range of the yard. the shell at the hole is soft. Help please.