I don't know if Crohn's can actually cause pain in the bladder, but for months I thought I had a bladder infection because I thought my bladder hurt. Not the type of "I can't walk pain" but a constant throb and yes, it hurt more with bms and urination. It turns out that it was the rectal region being so inflamed that I am feeling. My doc thought maybe I was feeling my fistula.
But, this sounds different because you are showing blood in the urine. My urine tests always come back clear. Wish I could be of more help, but just wanted to share my experience.
--39 year old female, dx as UC in '04 (1st symptoms in '03), switched to Crohn's in '05, 1 fistula, crohn's colitis, limited to large intestine
--rejected (reaction/didn't work): Asacol, AZA, 6-MP, MTX, Remicade, Humira, prednisone
--stuck on methylprednisolone, tried Prochymal in Phase III study (can't wait til it's approved!)
--started Tysabri 3/21/08
--single mom to 10-year-old girl