What Causes White Blisters On Tongue And Little Red Spots On Ankles And Knee?

my 3yr old has white blisters on her toungue and inside her mouth, she has little red spots on her knees, and round her ankles, also her bum, now she has had hand foot and mouth before earlier this year, but this could be the same but seems different to last time, she is refusing to eat and drink, all she had in 24 hours is 3 yoghurts but dont want no fluids, she so drowsy and wants to sleep all the time, i cant understand a word she says as she is crying and moaning that she is in pain. i have given her calpol.