A very painful mouth ulcer inside my left cheek has led to swelling and pain in my lower left jaw. It hurts to talk, eat, even sleep. Is this normal?

Worsening ulcer. Greetings. A worsening mouth ulcer possibly extending to the jaw needs to be looked at and biopsies. I'm not sure if you smoke or use alcohol but oral cancers are on the rise. A painful enlarging oral ulcer needs evaluation and SOON.
Canker sore. If new, probably canker sore. Treat with OTC pain meds, saline gargles, analgesic troches. If more than a week. See Oral surgeon or ENT doc.