I have an mouth ulcer that won't go away?

Man I've had ulcers all my life. I've had them on my tongue, all over my mouth, and on the back of my tonsil. Some lasted a few days others weeks. Many ulcers I've had were so bad I needed a steroid pack a doctor prescribed. Ohh and I don't have any illnesses or , just shitty luck. My recommendation is to wait it out. Stay away from acidic food (ketchup, chocolate, orange juice, etc.), brush your teeth a lot, and drink water.