Hope12,
I have the same urgency issue following BCG administration. The need-to-go can hit every 5 to 10 minutes, and output is small - 5 to 20 ml. My doctors tell me, "It can happen - the inflammation is what we want the BCG to do". It is no fun being tethered to the bathroom - adult diapers and a urinal may offer some mobility. Pyridium can help with urgency and urinary pain if OK with the doctor. Additional liquid intake can help with the pain and burning, but check with the doctor about timing a liquid increase after BCG treatments.
Always always - bring every concern, issue, problem or fear to your doctor or care team. If they don't hear from you, they can't help. Make sure that your requests for help get answered - there is no need for the road to beating BC needs to be any harder than necessary.
Best,
Jack