Canker Sore Relief while pregnant

I'm 16 weeks and ive had a two canker sores on the inside of my cheeks driving me crazy. So painful to eat or drink anything and I cant sleep because the pain is unbearable. I tried swishing with warm salty water, coconut oil, hydrogen peroxide rinse. The nurse at my OBGYN recommended I use benzocaine but I looked it up and it's classified as a category C which makes me nervous. Any suggestions for natural or OTC remedies that aren't risks for baby.