What Causes Fullness In Stomach While On Low Fat, Salt And Carbohydrate Diet?

I started a diet about a month ago, low fat, low carb..low salt. the past few days my lower stomach feels full with the need to go to the bathroom. Feels like a lot...but little feces is evacuated. I even have slight pain/sensitivity in my testicles, mainly the right, as a result as well. Nay suggestions??