Fear aggression in a puppy

I wanted to ask those of you who had a similar problem and managed to fix it. My 5 month poodle has always been scared of other dogs and a behaviorist told me to find her adult dogs who will teach her how to approach others. This doesn't seem to help when we are on our own though. She gets tense at ANY dog she sees and immediately starts barking. She is clearly terrified, tries to escape or howls if the dog approaches her insistently. If the dog is small enough, she might try to approach it, anxiously, and then after a minute of running away she will start to play or just remain calm in the dogs presence but then the cycle repeats with every other dog. What should I do to make it stop and just calmly pass by? Can treats help her with a positive association or on the contrary, reinforce barking? For now each dog is a huge event and we can't walk calmly. Should I just walk away and let her play so she gets the excitement out before we are able to calmly walk by the dog?