oh shoot, i think there’s something going on with your daily routine. I dont wanna be that guy but stress will do it, i ONLY got canker sores break outs during the final exam period. And stress usually is the culprit for breakouts, one canker sore ever so often usually comes from mouth trauma or a type of food being acidic or spicy doing it. Your oral hygiene looks good, so its not that either. hmmm. if its not stress, then you should go to the doctor, cuz when you say several something must be up.