It may just be temporary so don't worry too much yet. If you are using any of the shakes, bars, etc.. they could be the problem. They do stall a lot of people. Otherwise it is hard to say without knowing what you are eating. You may just need to experiment a little, cutting out certain foods to see what might be causing the gain. Cheese is also a problem for some people.
I had to cut out the coffee (Down from 2 or 3 a day, to one or two a week as a treat), no diet soda, and very limited cheese. I still haven't been losing as much as I'd like but I do feel a lot better and am loosing very slowly. My weight fluctuates a lot so have to not worry about ups and downs if the general trend is downward.
Hang in there