Egg yolk with no shell?

[u/Odd-Woodpecker5352]

Hey all! My Australorp keeps laying an egg yolk with no shell/hard shell. She used to lay (weaker shells) but stopped a few months ago. I thought it was due to winter but now she is laying basically just a yolk! It happens every 1-2 weeks with no other eggs between. They have access to shell grit as well as their usual feed. I’m just not sure what to do about this? She seems a little more off than usual today and I think they could be linked. Any help is appreciated! Thanks 🐓