I second that you can use toothpaste now as long as it is a baby safe one. You can get organic ones if you are so inclined. However my immediate thought is that she might have a bit of a tummy upset, as this will cause bad breath in otherwise normal toddlers (or at least it always has for my children). Alternatively she might have a viral throat infection but is otherwise asymptomatic.
By all means take her to the dentist, but I wouldn't worry unless the bad breath has been there for over a month or if you can see an infected tooth.
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