There are many treatments, but your best bet is prevention. I used to have mouth ulcers all the time, then I stopped drinking tap water and stopped eating store bought bread, and they went away. And what do these two things have in common? They bolth have ammonium-chloride in them. And if you’ve ever taken a chemistry course mixing ammounium-chloride and water creates a toxic gas, the same thing the Nazi’s used to kill people with back in WWII. Sure a little bit doesn’t hurt, but if you eat it and drink it every day you’re going to start finding 1 out of 10 people developing weird symptoms all the time.
90% 
Man… are you sure that’s not the number of patients that paediatrician treated whom had blisters which turned out to be herpes?
If that’s true, then Herpes must be like HIV; you don’t know you have it until you’ve had it for a looooooong time.
No, I’m sure this paediatrician has treated a lot more than 90 herpes patients. Anyway, chances are that you have the herpes virus, but its no big deal though. Many people show no symptoms of it and the big majority of people only get a blister or two, a few times in their lives, nothing as serious as HIV.