30ds + 30 mins cardio = weight gain!

So, I started the 30DS a few weeks ago and have also added in 30 mins of cardio every other day, I'm now on day 9 of level 2. When i started I was 192lbs. I measured and weighed myself on day 14 and had lost an inch off my waist, an inch from my hips and 3lbs bringing me down to 189lbs. I had my first day off since starting the programme on monday, (day 16, it's now friday day 20) and have now gained 2lbs!
I don't know if this is muscle gain or weight gain as I have been eating back near enough all my calories every day for the past week going from 1200-1300 a day to around 1600-1700 cals a day, I suspect it is the latter. I've gained back almost 1cm on my waist but I measured myself after drinking 2 glasses of water so maybe that's why I'm seeing an increase in my measurements there? Anyway, Should I decrease my calories or is this a normal fluctuation that most people see? I have no idea since I have never really worked out properly before!