My brother says I should get treated because once in a while I get oral ulceration? Is he right?

Oral ulceration. The most common form of occasional ulceration in the mouth is a canker sore (aphthous ulcer). There is no really good treatment for these (although lots of things have been tried); most people just wait them out for 4-7 days. Unless you have unusually severe symptoms you do not need to be treated. If, however, an ulcer were persistent and chronic rather than occasional, then it should be checked.