I am a 55 year old woman. I am 5'6" and weigh 159 lbs. I suffer from fibromyalgia, cervical and lumbar spine injuries, hyper mobile joints and autoimmune disease that affects my joints and muscles. I  have lost 50 lbs this year, but it was due to stress and lack of appetite. Now I have no muscle tone (actually, not much muscle at all). I also have very weak abs and excess ab fat and loose skin. I would very much like to strengthen my core and improve my muscle tone, but haven't found much I am able to manage as far as exercise goes. Is there any help for me?