I'm sorry, but anything besides their formulated feed should only be given once or twice a week in minor amounts, less than a tablespoon per bird.. Scratch and seeds are high in fat and carbs, chickens gather fat around their internal organs, like around the heart and liver before they lay...
She should not have free access to seeds and scratch, they're not great for her and keep her from getting enough of her formulated feed I'd she eats it. That's why her shells are weak. Seeds and scratch are treats to be given in minimal amounts one or twice a week.
I suspect she's Suffering from...
At that age and diet, she may have a broken egg in her.
How often and how much does she get the seeds and scratch?
Sex links are prone to reproductive issues that can typically start cropping up at 2.