My son has a terrible time with them too. They used to get huge and take 10 days to go away.
Much better now though. We use "Orabase" on them. Also, he gets fewer and what he does get go away faster since we started using "Rembrandt Cancer Sore" toothpaste. Hard to find a the stores now though, so have been ordering from drugstore.com.
I'll have to check out these other ideas too though. Still some struggles, especially in the spring. (No idea why this would be.)
E.