I don't know about the Pepto, but you can give her one of those simethicone remedies, like Phazyme. At 70 pounds just give her one of the regular strength gels, not an extra strength.
If this is a problem all the time you need to address it at her food dish. That's where the problem originates 99% of the time. If you ate something that routinely gave you gas you'd stop eating it all the time, wouldn't you?