I've had the very symptoms you're experiencing and it sounds suspiciously similar to the condition I have. Much like you, the symptoms came on suddenly and it was excruciating. It sounds like you may have Interstitial Cystitis. It is also an 'idiopathic' condition that is linked to autoimmune function within the body.

This is a great website that gives a good overview of symptoms, helpful hints for alleviating the related pain/discomfort, tips for diagnosis, etc:

http://www.ic-network.com/handbook/basics.html

I first experienced these symptoms in 1998 and had excruciating pain for about 8-10 months before I realized that this condition was what I had. Then I learned some coping mechanisms that helped immensely. I did not end up taking any prescription meds, but rather found a natural route (including the supplement Algonot that they mention on the site). At this point, I usually have a 'flare up' once or twice a year.

Good luck to you,

Andrea