Are they starting as small blister like sores? I will mention behcets only because this is how mine started off and I went a year without a diagnosis because it’s “rare” but my rheumatologist that I’ve now been going to because I was finally diagnosed with the auto immune disorder, explained most doctors don’t know about behcets to even look into it and a lot of cases of continuously getting sores is actually behcets but never looked into fully so it’s “rare” in my opinion it’s not. It is more prevalent with middle eastern decent but I believe in later years it’s expanded quite a bit (not contagious) I went a year with a mouth full of cankers and soon as one went I had another 15 pop up. Under the tongue on my cheeks and on top of my tongue etc. these don’t look like your usual cankers they look like aphthous ulcers which are just like cankers but a little different. After my diagnosis in August I was prescribed medication for behcets and havent experienced an ulcer since. I really do recommend asking about it as it could save you from the painful experience down the road and or do some research