How old is she? Is she acting listless? Moving slowly like something hurts? Tucks her head and sleeps all the day? Stays by herself?
I started with 6 Ideal Easter Eggers 3 years ago. After this last winter, one was listless and moving slow. I was told that it takes time to get the egg machine pumping again. She started laying soft and then rubber eggs a couple months back. Finding several shell-less eggs in the nest also. I culled her and she had several masses in her abdomen. Search lash egg to see what I saw. The pictures, advanced cases, will be with the Leghorns that I nursed. No recovery from these. I lost 3 of the 6 Leghorns to this.
That is the worse case. Best case, she is getting the machine pumping and will recover. If it goes for a month, I'm afraid we are past that.
In short, there is a chance that she has issues in the plumbing. Can be called reproductive tract cancer or infection. Bottom line is that it is fatal.
Best wishes with what you decide. I learned and choose not to prolong the suffering. Beautiful creatures these chickens.