WORMS??- Thin Chicken, Loosing Feathers

[44Wolves]

My 38-week old Olive Egger has been getting very thin and losing feathers. She may be getting picked on, as I have seen her getting picked at a few times, but she's missing feathers all over. I can feel her bones when I pck her up, and she is so much lighter. Yes, she will eat and drink fine. She is broody right now on a nest of golfballs, so maybe that is why? But this is a lot of weight loss. I can see extra skin underneath her from where there was once more weight. Could this be worms? I have never treated for worms.

I'm leaning towards worms. If so, what should I use?
-38 weeks old
-3 other healthy chickens
-never been wormed before