My 1.5-year-old black sex link started laying deformed eggs several months ago. They would be banded in the middle and have other swirls etc. The shells are always thin. Once or twice a week she would lay a shell-less egg that I would find below the roosting bar. This has now developed where she is only dropping shell-less eggs at night and has not laid an egg in over a week. One or two of my other chickens in the flock have some shell quality problems such as rough shells, but nothing like this one. I was doing a search on the Internet and saw this phenomenon of egg drop syndrome. The last article written on it seems to be 1976 when they said it did not exist in the United States, but it has been 50 years since it was written and I assume that perhaps it has reached the US by now. I am considering removing this chicken from my flock if this is permanent. Any advice?