Do a body cleanse detox for fast weight in a week, but then you have to keep up with working out and eating healthy after that to keep the weight off.
It's really expensive though because you want to only eat juiced up fruits and vegetables and that is all you eat for a week.
Gahh all this should help. Last summer I was 5'2 and weighed 110 lbs. I gained 20 over the winter and I need to lose it all before summer vacation starts, that'd be in a month and a half.
I started taking medication not for weight loss and lost 20 in 2 weeks, it basically eliminated my diet so I had to force myself to eat, eventually my stomach just shrunk, so I eat enough to make myself full and I maintain a muffin top/ fat free body. But you really do need to exercise too, I swim a lot so it helps me, I haven't been fat since the ninth grade ever since I went on my health kick
If anything, you should start with cutting out junk food and sodas in your diet.
Exercise/Cardio wise, you should pace yourself and build onto what you can handle.
Make sure you stay consistent, because if you slack off, it'll be hard to bounce back.