It takes less than three days of accidentally using toothpaste with that stuff to cause me two weeks of miserable mouth hell from all the ulcers that form.
We were on a group trip for about a week and had forgot their toothpaste and had borrowed someone's 'natural toothpaste' stuff. By the end of the week they were far more intelligible in speaking and were stating it felt like they mouth deflated. They had an undiagnosed allergy to toothpaste their entire life and no one had recognized it.
Yes, and also get a generalized allergenic test since you are obviously alergic to something and it might be a lot bigger group than you think.
Relatively dry mouth. Milk of magnesia. Q-tips. Paint the sore spots with MoM. It thickens and forms a film, which cuts down on the tenderness.
I would try one spot if I were you. As bad as you described it, if that helps more than it hurts you might try gargling the stuff.