If this has appeared in your mouth, you should be very careful because…

Possible causes of “this in your mouth”:
If you’re referring to sores, canker sores, spots, or bumps, it can be caused by a number of reasons, including:

Canker sores:

These are usually small, painful lesions inside the mouth, caused by stress, minor injuries, vitamin deficiency (such as vitamin B12), or even viral infections.
They’re usually not serious and heal on their own within a week or two.
White or red spots:

These may be related to infections such as oral thrush (caused by fungus), or irritation from smoking, drinking alcohol, or accidentally biting yourself.
Cold sores:

Caused by the herpes simplex virus, these appear as painful blisters on the lips or around the mouth.
Severe or persistent lesions:

If the spots or lesions don’t go away after 2 weeks, it’s important to see a doctor or dentist, as it could be a sign of more serious conditions, such as oral cancer. Why is it important to be careful?
The mouth is a sensitive area and many conditions can get worse if not treated in time.
Some signs may be symptoms of larger health problems, such as systemic infections or immune deficiencies.
Recommendations:
Maintain good oral hygiene: Brush at least twice a day and floss.
Avoid irritants: Limit the consumption of very acidic, spicy or hard foods if you have mouth sores.
See a specialist: If you notice something abnormal in your mouth that does not improve, visit a doctor or dentist.
Avoid self-medication: Home remedies can temporarily relieve, but they do not always solve the underlying cause.