My Daughter Age Is 3 Years,, As Of Now She

My daughter age is 3 years,, as of now she is not habituated to eat rice and spicy items, she always prefers to eat chocolates and soft items..major problem we are facing is she cannot go toilet daily..once in 4 days she will go and she does not prefer to go in bathroom and some other place..she prefers in dipers and clothes with lot of pain..please advise to over come this problem.