Hi. I would also suggest getting a positive trainer in to analyse the situation properly as it's difficult without getting more detail. Sometimes dogs on lead suffer from frustration rather than fear aggression and a trainer would help you with.
In the mean time, try not to let her practice the behaviour as it becomes ingrained and more difficult to change. Keep big distances from other dogs, we cross over roads, hide behind cars, walk in opposite direction, teaching a 'this way' as you turn so the dog gets used to it. I counter condition Maddie, so as soon as we see a dog, but before she reacts, I feed her high value treats, such as chicken. This keeps her attention until we've passed the dog. Now as soon as she sees a dog, she looks at me for her treat and I say 'watch'. The idea is that when a dog sees something scary, they get a treat so changing the emotion.
A trainer would advise about a muzzle. I have muzzle trained Maddie as I think it makes me feel less anxious, but don't use it very often as I tend to avoid places where dogs are likely to scare her.
Hope this helps