I might be wrong, but I'm sure i spoke to you the other day too, maybe about a cheek issue? Is that correct? I would have also stated i worked in a dental setting for years.

If you are that person, it's sounding like you're stressed or run down (post viral infection etc), which both can and does cause cheek biting and ulcers. Ulcers can linger for more than 4 days. So that doesn't really sound worrying at this point. It's if they don't settle in 2 weeks you go.

If you are finding yourself getting lots of ulcers in quick succession, and it isn't any of the above, it's more likely down to an autoimmune issue, not cancer IF it were to ever be anything out with the norm. The only other thing that can appear separate from those is something called Acute Necrotizing Ulcerative gingivitis (A.N.U.G). That can appear as ulcers around the teeth. But you'd know all about that as it's painful as painful can get.

All that aside, you seem to be having a lot of health anxiety surrounding your mouth, and the fact you're here means you're jumping to the worst case scenario each time. It sounds like you're needing to see your dentist, then go from there. Maybe you need a mouthwash such as Corsodyl.

To be clear, an ulcer that has been present for 4 days is almost always nothing to worry about. But you're needing to see your dentist so you can get to the bottom of what is happening if it's impacting on your life. No one can tell you what may or may not be causing your issues.

EDIT: Forgot to mention, this might even be an issue with the tooth. Go to the dentist.