When you say she "hasn't laid an egg in forever " it could point to her being egg bound or laying internally. Which might be why she is sitting around with her eyes closed not really wanting to move. Please check into these as possibilities. You've gotten a lot of good ideas here but I don't think any of us are vets. Unfortunately the longer you have chickens the more you'll gain experience diagnosing and treating them, but they often don't show any symptoms until they are very badly off.