I would feel a normal chicken first - just so you know what is a bone and what is something abnormal. I would first try feeling on the outside of the chicken - have the chicken face you and press/feel lightly starting a little before her legs and going back - be sure to feel between the legs and...
When was the last time she laid an egg? if it has been a couple days, she could be egg bound, where the egg is stuck in her and she can't pass it.. Feel for any abnormal lumps. If you feel one, soak her in WARM water and epsom salts for about 15-20 minutes. After she's soaked, gently towel dry...