L.K.
I believe it's the coxsachie(sp?) virus and I used a product high in lysine, Herpanacine. It was a capsule and I opened it up and sprinkled it in applesauce or yogart. I used about 1/3 of a capsule, 3X a day. It really boosted my son's immune system and he cleared up within a few days.
The other possibility, it may not be hand, foot, mouth.
Good Luck!!
LaurieK
www.mymonavie.com/LaurieK