Excessively hungry and gaining weight?

For the past couple of weeks I have been eating non stop. If I got to long without eating I feel sick. Iv been gaining weight and I have to fit I to my wedding dress in 3 months. All I want is unhealthy food. I used to eat somewhat healthy and lots of water. I barely used to eat junk food and now that's all I want... And I don't even want water anymore usually pop. Anyone have an idea of what could be going on?