My 1.5 year old barred rock has been laying eggs with a very thin shell for a few weeks. The last week the top of the egg is consistently paper thin and cracked. She’s a heavy layer, one xl egg every day and hasn’t taken a break since she started laying. She gets purina organic layer crumble feed, and next to no treats, minus free range bugs/greens for a few hours a day. Free oyster shells always available. All other birds are laying fine? Something else I should be doing for her, or is this just an individual bird thing?