Hiya Lali
Have you eaten in the 2nd week as a 6 pound gain would indicate that you probably had?
It isn't unheard of to have a slow week in the 2nd week but everything usually settles down in week 3, just remember that you will lose weight on this diet, it works for everyone and when the scales stop moving this is due to water retention and other factors, it isn't that you aren't losing fat.
In terms of exercising the advice I always give is that the exercise should be conversational, i.e. you should be able to talk perfectly normally while doing it so examples would be walking, gentle swimming, yoga, pilates, toning and stretching exercises and generally getting more active without going mad at it, if you do much cardio work then you will find your weight loss plateaus and you usually feel like you have flu!
Give your CDC a ring for a chat as they are there to support you especially through the first couple of weeks while you get into the diet but hang in there, this is life changing stuff and you will be slim if you just keep glugging the water and eating the packs.
M.