I have a white patch inside the mouth

[sourav333]

I have a white patch inside the mouth (At the left surface of cheek and at the back side of my side teeth,)

I have these symptoms

Pain(When my side teeths touch it or during eating foods)
Burning sensation
Discomfort

[specialmom]

Those are canker sores most likely. Everyone gets them from time to time. They are not serious. But yes, uncomfortable. They normally go away in a week or two although you may have new ones after that. These are some things that may cause them:
    Certain mouthwashes or toothpastes
    Dental work or brushing your teeth too much or too hard
    Food sensitivities
    Hormonal shifts during your period
    Not getting enough folate (also called folic acid), iron, vitamin B12, or zinc
    Stress
    Anti-inflammatory drugs like ibuprofen

Do you have IBS or gastric, digestion issues? Any autoimmune issues?  

Here are some remedies:
    Avoid acidic or spicy foods.
    Brush your teeth gently.
    Put ice on your canker sore.
    Putting a dab of magnesium hydroxide on your sore a couple of times per day.
    Rinse your mouth with saltwater or a mix of baking soda and water. (Mix 1 teaspoon of baking soda in half a cup of warm water.)

https://www.webmd.com/oral-health/ss/slideshow-canker-sores

I personally try not to eat much citrus if I have canker sores as that aggravates them.