Not too sure what the medical problem is but I injured my knee really badly before and found swimming was the only exercise I could do for a while! The water means there's less stress on your foot plus swimming is great for toning muscles and cardio. If this isn't for you just doing crunches, situps, etc should help you tone up.
It's hard to target just one area to lose fat in, but if you eat healthy (no fried food, try grilling or baking meals, eating lean meats and fish, vegetables, soups) and portion control the size of your meals doing, as you lose weight you'll be able to see the tone from the exercises you've been doing.
I'm not great with diets but soups are a good trick to getting you feeling fuller for longer! You can find heaps of healthy low-calorie recipes online.
All the best!
Try eating veghies and food that are high in fiber