Your BCG experience sounds similar to mine, and the effects can slowly increase.
It helped me to know that the worst resolves in 12 to 14 hours after the first void.
During those first hours it helped me to drink fluids, even with little return. Warm liquids (coffee) is my favorite.
I would get comfortable in bed, and place a urinal to receive the few ml + clots & tissue, and put a hot towel or microwaved heat pad over the bladder and TRY to relax through the urgency. Some time in a hot shower, with pressure shifted to other parts of the bladder while standing was sometimes a help.
I never quite figured out a pattern, but changing position - sometimes - seemed to help quite a bit, at least for a little while. I'm sure we are each different. I started on Connaught BCG and was switched to TICE BCG after 9 instillations.
Hopefully, Tokyo 172 will do the trick.
6/2015 HG Papillary & CIS
3 Years and 30 BCG/BCG+Inf
Tis CIS comes back.
BC clear as of 5/17 !
RCC found in my one & only kidney 10/17
Begin Chemo; Cisplatin and Gemzar
8/18 begin Chemo# 3
Begin year 4 with cis
2/19 Chemo #4
9/19 NED again
1/2020 CIS is back
Tried Keytruda, stopped by side effects
Workin on a new plan for 2021