I had BCG chemo for bladder cancer & developed serious infection requiring hospitalization. What other chemo drug can be used?

It depends. Bcg sepsis is a known, yet uncommon complication of BCG treatment for bladder cancer. The next option really depends on your specific bladder cancer - your urologist will be bettre ablet o discuss this with you. The next option may be for intravesical mitomycing, intravesical valrubicin, or possibly cystectomy.
Ask the experts... Please discuss this with your oncologist; there are so many chemotherapeutic agents available, and without knowing the rest of your medical history, you should have the specialist treating you help you make this call. If you are unhappy with that you can always get a second opinion.
After BCG. The BCG is attenuated tuberculoisis, and does help many superficia bladder cancers stay put. If your bladder cancer remains not invading the muscle, in the bladder Mitomycin has been used. If it invades the muscle, time for discussion about bigger systmic chemotherapy, bladder preservation, or bladder removal.