Hello Madam, I am sorry to read about your troubles!
This kind of lesion in the mouth can occur following an episode of illness, stress, fatigue, consumption of an irritating food or irritation with an object (utensil, toothbrush, etc.) but usually goes away on its own.
Taking acetaminophen (Tylenol and other brands) can relieve the pain. What you can also do on your own is to use a soft wire toothbrush, and favor an alcohol-free mouthwash if you use one, and avoid spicy or irritating foods such as coffee, alcohol, juices and spicy foods
A paste like Orabase can help reduce irritation when you eat, and does not require a prescription.
If the situation persists for more than 7 days without improvement, I suggest consulting a doctor.
I hope this helps, and I am available if you have any further questions!
Tom Samaha, pharmacist