The way you tell is that you lift it up by it's body. If the their claws retract, it's a rooster. If they are left dangling, it's a hen. Rooster are defensive. Hens are not. I was taught this at my local supplies store.
What I know is that I have a black hen that has outlived others from two hawks and a fox (I was 10 feet away from the second hawk attack). Because of issues with hawks, I no longer free range.
There are some things you can fix, some things you can't. If she is egg bound, a relatively easy fix. I had something similar happen to one of my chickens. I thought she was egg bound. I took her to the vet. She had an enlarged gizzard that was basically suffocating her. I'm so sorry about...