Recent research articles say that lemonade is one of the best ways to prevent kidney stones. You can make up The Master Cleanse drink per the diet, make lemonade using a natural mineral rich sweetener (I like evaporated cane juice over processed sugar) or simply juice a fresh lemon and add to hot, not boiling, water. Eating Asparagus is also reputed to cleanse the kidneys and eliminate stones. Celery Seed Tea and Watermelon Seed Tea have also been recommended as extremely cleansing. What ever you do, I would suggest that you take some form of fresh lemon juice daily.
Since you also have weight issues, I would suggest you try a ten to fourteen day Master Cleanse as soon as you feel able. It cleanses the whole body, allows you to drop some weight, and prepares you for correct eating and safe and permanent weight loss.