Not sure if I have the stomach flu or the indian food I ate didn't sit right. Can I use pepto bismol (bismuth subsalicylate) to help?

Sure, no harm there. If it's food related there may be associated diarrhea, and will be limited to 12-18 hrs. Try to stay hydrated. Either way it should be self limited. Of course, if symptoms worsen or persist more than 2-3 days, i suggest you contact your provider. Good luck.