I just had a bout with constipation and irritable bowels. It was quite painful. One of the worst parts is that with the fullness, I had to urinate more due to the pressure on my bladder. I'm a male, but I can relate to the pressure you are experiencing. After 2 days of prune juice, I finally broke down and took a laxative which worked after 2 doses. I am so glad that is over.
I don't know why these things happen. I take care of myself, don't have much stress, exercise (strong abdominal muscles), and eat as well as I can. It doesn't happen often, but when it does, it is persistent and a real painful nightmare. And, I find it embarrassing, as well.