Hen laying odd formed eggs lately

[tralfaz]

For about a week, one of my 6 hens has been laying misformed eggs. She's about a year old and a hybrid RI. Shells are hard not soft like they look. We use Purina Layena. Other hens seem to be doing fine.

 

[BDutch]

https://www.backyardchickens.com/articles/common-egg-quality-problems.65923/?page=5

Paragraph Nr 13

 

[BDutch]

I think I read somewhere such eggs can be formed after an infection. I try to look it up. Maybe it was an article about deformed eggs.