Yes, a flare can last longer than one day. Or it can start as a bad flare up and then just linger a while as a kind of slightly sensitive gut for a week or two.
Perhaps you introduced foods that irritated your tummy too soon?
Usually when I have a flare up I have to be very very gentle about what foods I eat, for a few days and try to eat very bland foods until things steady out more. Just beginning to come out of a bad flare up day isn't the time to re-introduce foods that might irritate your tummy, or to try to experiment with what seem to be more "healthy" options.
If you take a vitamin-mineral supplement daily you won't need to worry TOO badly about having a restricted diet for a few days until your tummy settles, as that will be a small safety net for your nutrition.
I am alwats reminded of when I had a dog. If she got any upset tummy, the vet's advice was to fast with water only until the bad symptoms started to subside (usually diarrhea and/or sometimes vomiting.)
Then when she was obviously hungry, to start with small amounts of white rice only, see how that went. If all was well, then introduce plain boiled or steamed white fish or skinless chicken, and to stay on that food until the gut started to come back to normal, then gradually to re-introduce her normal foods bit by bit over the following days.
Now obviously we aren't dogs, so that idea has to be adapted for us and we can probably eat some other things like bananas, toast, or some easy to digest bland food that suits us, but it's the same principle.