I learned instinctively about the water (drink lots anyway), and my chiro advises on probiotics in cases of infection.
But didn't know re baking soda and avoiding fruit and vitamin C (in mouth ulcer cases -- although it makes sense).
[In your spare time (LOL!) you'll have to guide us on what the heck to do with different manifestations of colds and infections: the head cold, the sore throat, the cough and fever... Oh, there are so many! I imagine probiotics, baking soda "toothpaste", tons of water and zinc work for all. (and good thoughts, too!)]
I've cut and pasted your tongue ulcer notes into my file.