DD, who is 3, had threadworms, so I have given her(and us all) a dose of covex, she stopped waking up in the night screaming so I think it must have worked but last night she woke again saying her bottom hurt. it is only a week since she has the first dose, do I have to wait another week until I give her a second dose or do you think she can have another dose now? I really don't want it to come back again!