Oral ulcers are minor and major ulcers.
Usually recurrent ulcers are minor ulcer we call, especially if it's not there in hard palate and there is no other systemic issues.
In my Gastroenterology practice what we do is, clinically asses for any features of any other Diseases.
If nothing, I ask for some basic tests like CBC,
vitamin b12, Folate levels, ANA-IF and stool test for H Pylore
After seeing this will decide regarding need for any Endosocpy or colonsocopy.
Regards.
Get well soon
Dr. Sanoop Kumar Sherin Sabu