I'm halfway through my first BCG treatment (had treatment #4 on Wednesday!). The first two weeks were fine, just some minor cramping the first day. After treatment 3, I was thrown for a loop. Monster level fatigue, headache, achy all over. I went to my urologist when I couldn't take it anymore (meaning I couldn't power through and go to work) and he gave me a broad spectrum antibiotic (just in case) and a day of rest. That week's treatment was cancelled due to it, but only for a week. Urine culture came back negative for bacteria, and I did feel fine in a few days. I think it just hits some of us harder than others at random times. Good luck.
Heather
Diagnosed 5/25/2016
First cysto and TURBT 5/23/2016
Nephrostomy placement 5/24/2016
Second cysto and TURBT 6/20/2016
Papillary urothelial carcinoma, mostly low grade
No stromal invasion, no metastasis
Original tumor size (by CT): 7.3 cm x 4.8 cm x 4.8 cm
Starting BCG 8/21/2016