Pixie91
Do check with your care team - they may be able to prescribe medication, depending on your particulars, to help with BCG symptoms. Being without one kidney can make a difference in the speed with which the bladder is flushed following BCG instillation.
ALWAYS talk to your care team before trying anything you read on the net.
I reach badly to BCG, and have found the following helpful.
Lying down during the spasms, placing a hot (not scalding) pack over the bladder.
Walking when the urge is great but no urine is forthcoming.
Drinking just a bit beyond thirst for the first 4 hours after initial void (or however long your doc wants you to NOT drink to excess).
Increasing liquid when allowed, but not so much as to over-run my one kidney - balancing input and output to get the best flow through the kidney and bladder. Doc discussion necessary.
The non prescription drug Pyridium aka AZO or Urinary Pain Reliever can help - again check with doctor.
You will need to find what works best for you - stand sit lie down - walk, hot or cool showers, aspirin or other pain meds if allowed.
Alan already mentioned dose reduction, if the doc agrees. It seems to fairly well accepted that the full dose should be used for the initial 6 BCG treatment if possible.
BCG treatments have also been spaced farther a part because of individual reactions, bleeding and severe bladder reaction are generally accepted as a reason to hold off on a treatment for a week or so.
If I receive BCG in the morning of day one, it generally takes until about 1 AM the following day before urine is flowing and i know that the worst is over. two or three days (or more) with variable symptoms follow.
I hope this gives you some ideas to talk to your doc about, and things to try to ease the post BCG period. Make sure to discuss fluid intake and effect of having only one kidney. It is the function of the docs and care team to get you through treatment as easily as possible - get them involved.
Best
Jack