Hand, foot and mouth blisters: what happens to them?

[linspins]

My 21 mth old has this, and is pretty miserable with it. Some of the blisters on his feet are biggish. I am wondering: what happens to the blisters? Do they get bigger and then burst? Or just fade away? Is he going to get horrid weeping sores on his hands and feet?
Also, does anyone know the best stuff to put in his mouth to help the uncomfortableness? Is Bonjela suitable for toddlers? (Assuming he'll let me get anywhere near his mouth!)

I seem to remember they just sort of dried up - no bursting. Calpol, calpol, calpol... My gp said you can do 10ml when over 12 months.

Thanks. Gave him Calpol and Nurofen in the night, he was really miserable. Tired Mummy today.
I will watch the blisters carefully...