Layers pellets/mash is specifically designed to have all the nutrition a laying hens needs, by giving them other treats you are actually changing this ratio. just give them the correct feed for now, egg laying takes an awful lot out of young birds and they need the correct nutrition. also have a small bowl of grit/oyster shell available for them, they will take what they want, when they want it.
The strange eggs will eventually sort itself out, mine still throw an odd leather egg and they are a few years old.
The strange eggs will eventually sort itself out, mine still throw an odd leather egg and they are a few years old.