Thanks for using JustAnswer.com, I'm Dr. Dan and I'll try to help you.
It is best not to use Pepto bismol® in a cat because most forms of Pepto bismol® contains components of aspirin that do not set well with cats. If you feel your cat is gassy and bloated the best thing to use is simethicone or infant gas drops. This will be safe and help if your cat is truly bloated and gassy. If this doesn't help with in 12 hours and your cat still seems affected then it is time to see the vet. I hope this helps, best wishes.