There's no way to tone skin; whether or not you have lose skin really depends on your individual genetics and age. There's no such thing as a skin exercise!
Likewise, you can't spot reduce any area of the body; you can strength train, and build up the muscles, but there's nothing you can do for your skin. If you get lose skin, the only thing to do with surgery. ;)
However, I am concerned about your medical issues; have you discussed your exercise program with your doctor and gotten clearance to exercise?