You stop losing weight when your calories in equal your calories out. To get back on track first go see your surgeon and see how much is in your band. The band does not work by restriction - but appetite suppression. So the purpose is to now refine what you eat, and decrease it. Things to get rid of: soda, ice cream, yogurt, and more than 4 ounces of protein per meal. Things to add: fruits and vegetables. Good luck.
Sudden loss of restriction to eating can only mean one of two things. Either your banding system has gotten a leak and all the fluid has come out, or the band has eroded into the stomach. You should visit your doctor and have it checked out.