I agree with the other posters who said you should go see your doctor. You can never go wrong with asking the doctor for advice if you feel your body is doing something different or weird.
That being said, I had a partial hysterectomy in July of 2006. I weighed about 125, maybe 130 when the surgery was done. The doctor said to wait 8 weeks to work out after surgery. I didn't listen, busted my stitches and almost died in the hospital. But, that's another story...
Now, I weigh close to 150. I have a particularly protruded stomach, and several people have asked me if I'm pregnant, because I look about 4 to 5 months pregnant. I work out 3-5 days a week, and I concentrate on ab exercises.
I eat less than I ever have, and I've been making sure to add fruits, vegetables and fiber to my diet. When I complained to the doctor, she said, "Some people just gain weight after they have a hysterectomy. We don't know why."
I eat small portions and feel over full, almost sick when I finish. Food is not enjoyable anymore, and the exercise is just starting to frustrate me.
If you find out what is going on with your abdomen, I hope it can be reversed. I'm so frustrated with mine right now. I don't regret the surgery, as it was medically necessary when it happened, but I have never looked like this before in my life.
Good luck with your problem. I wish I could give you a solution, but if nothing else, please know you are not the only one going through the frustrations.