My Mom has been on steroids (prednizone) now for 9 years. She has addison'* disease and her body doesn't produce any adreniline and you obviously need it to live. She also felt the way your Mom is feeling about her body. I believe my mom gained 150lbs in a little over a year on them. She still takes them but at a lower dosage and she has finally lost all the weight (down back to 135lbs) and got her strength back.
I hope your Mom gets better soon. I can't imagine how she feels, but I have an idea due to my mom.
Your Mom will still be in my prayers