What is your normal day of eating like?
What is your average work out? Do you exercise consistently?
Do you make sure you drink more than enough water?
Gaining 6 pounds in four weeks should not happen, unless you have excess water weight or somehow gaining a lot of muscle really fast, which I sincerely doubt.
Although, I do have to say, when I was 245 lb, I had times in which I gained when I was working the hardest to lose weight, and then when I relaxed I lost. Which I still do not understand.