Ask a chemist — they’ll tell you that Bonjela isn’t really much use in comparison to Adcortyl in Orabase
I used to get em regularly and then followed advice to cut out toothpastes that contain sodium lauryl sulfate. SLS aggravates minor gum damage and turns it into an ulcer. Also acts as a skin irritant for some people. Details of clinical study below.
It worked for me. After about 4 weeks away from it, I stopped getting ulcers.
Herlofson BB, Barkvoll P (June 1996). “The effect of two toothpaste detergents on the frequency of recurrent aphthous ulcers”. Acta Odontol. Scand. 54 (3): 150–3