Yes to the suggestions to get her checked and also spay her.
Aggression may not necessarily be vicious but rather reaction to the scary situation she encountered. It can be dealt with through consistent and regular training (with treats to start) - you might try the Fenzi Dog Academy online classes (they have a great class for retraining reactive dogs). But regardless you need to be more aware of her surroundings and not put her in a situation that may be scary to her or at least get her attention back on you (treats) when you can't avoid the situation.
