Recurring blisters, sores in my mouth- sign of a larger issues? 19 y.o. female

Canker sores: No one knows exactly why canker sores occur, but they are often secondary to an infection somewhere else in your body, or to stress, or to eating too much spicy or acidic food. I prescribe a liquid concoction that my pharmacist compounds for me; your dermatologist probably has something similar. Prevention involves discovering the cause and eliminating it.