I'm no dietitian, but i think it would be almost impossible to gain 6lb in only 3 days, that would mean you've consumed 21,00 calories more than you have burnt off. It's more likely that when you originally weighed yourself you were at a particular low weight as your weight naturally fluctuates during the day and when you weighed yourself on the second occasion you were at a high point, or maybe your scales are faulty. Pretty sure if you stick with it you will lose weight, good luck