Interesting problem.
Usually when I ride, I don't have to urinate for hours, even if taking in alot of liquids. I sweat alot and I think no matter how much I drink, I always get alittle dehydrated. If I start a ride at 9 am it's not unusal for me to go to about 3 - 4 in the afternoon before having to use the restroom. But I don't have the discomfort you experienced. Something you should definiately discuss with your doctors!