Daughter,
While the initial diagnosis is bad news, it is not the worst news. Caught early there is a great likelihood of controlling or eliminating bladder cancer; keeping it at bay will be a lifelong chore.
With a lack of other pain control options before the biopsy, heat is an alternative, as is increased fluids so long as urine remains flowing. Moist heat from a microwaved or steamed towel placed over the bladder area can help - massaging the area may also help. A soak in a warm tub may provide relief. Try, see if it helps.
Best
Jack