Remember you didn't put the weight on overnight, so it won't come off overnight either. I agree that the chances you actually gained 5 pounds in 2 days is highly unlikely. That means you would've had to eat 17,500 calories above and beyond what your body used in those days. (5 lbs x 3,500 calories for 1 pound of fat)
I don't know if you're weighing every day but if you are, may I suggest you do it once a week? Our weight can fluctuate naturally from day to day and if you weigh yourself daily, you may just drive yourself nuts.