I remember near gargling SM33 as a kid, the ulcers would go all the way down my throat. The original Listerine seems to stop them in their tracks, just getting back down off the ceiling after the first swish is the tricky bit. I did suffer from mouth ulcers a lot, tomatoes were a sure fire way to end up with a mouthful, but that doesn't seem to happen much these days, but the sun blistered lips still catch me every so often
Try adding rhubarb to your diet and mushrooms, they are both good for reducing the number of ulcer outbreaks and cramps as well as herpes simplex, cold sores. Sun blisters on the lips are different to cold sores, feel a bit the same but can lead to much more serious complications.
The old zinc cream on the lips as used by life savers and cricketers is great for stopping the sun burnt lips ..... just tastes bad and I seem to forget to put it on for some reason
T1 Terry