Hi Neil,
Over a period of about 12-15 months I had 18 BCG installations (7 yrs ago)…all clear now for nearly 6 yrs. I had 3 TURBTs in total…2 recurrences, and each time the tumors were under 3cm. I did not experience what you’re going through other than a cold/flu like symptoms which lasted 24 to 48 hours after each treatment.
It may be an infection as you suspect but I would call your URO just to check it out. You didn’t mention if you had a follow-up cysto since your TURBT a year ago but I would expect that would have occurred.
Your bladder has gone through a lot and items such as coffee and citrus drinks will aggravate a sensitive bladder. I would stick to water for awhile but in the meantime I think connecting with your URO would be appropriate.
Stay positive, stay strong…god bless.
Rick