Well, you'll hate this advice, but, it is working for me:
Walk her alone, NOT with Oliver. You need both hands available to work with her, and no other dog distracting you.
Next, buy a clicker, a halti, (gasp.. really!) some unbelievably delicious, small, moist treats (cooked chicken is good). Order Feisty Fido by Patricia McConnell. This book will help you until you have a great trainer onboard-- and even afterwards for neccesary homework to solve this problem.
Begin working on teaching focus at home using the clicker and treats. Get that Watch command good and solid!
When I walk Grimm, I have my lead and clicker in one hand, treats in the other, and go to The Zone of Many FiFis.... a very doggy area in my city. When Grimm first sees another dog, I use the halti to g-e-n-t-l-y turn his head in my direction after I say Watch. Click, treat. Repeat. Then, things get interesting!
I ask for a heel! A sit.. a down! A dancing heelwork figure 8-- who knows what I'll ask for! Grimm gets a click and treat EACH time he looks at me and or does what I have just commanded. And.. those commands come FAST! He had better watch Mama.. because we will heel left, right, around in a circle right into his space going left.. etc.
Grimm thinks: "Whoa.. no more harsh, stressful prong collar corrections when I see another dog. Seeing a dog = busy, busy, busy.. better watch Mama, commands will be happening fast! We'll be DANCING! Plus, I get major boku yummy TREATS.. and tons and tons of praaaaise! Man.. Other dogs don't make me tense up and bark so much anymore!"
The halti removes any tension YOU may have been sending to your dog using a harsher collar when he reacts to another dog.
The clicker takes you, and your tense emotions, totally out of the picture, and calmly says 'That's right' each time she does something.. calm, positive, cut-and-dry-- easy.. PLUS-- it tells her she is working, and in working mode.. not freak-out mode.
The treats and praise create a positive association with something she normally finds stressful.
The zippy fast heeling, sits, downs, comes, etc etc all changes her mindset about what her rutine will be when she sees a dog. Freak out? No! Work time!
For snacks and praise!
A better option.
Please order Feisty Fido.. it has helpsed me considerably.I hope you find a great trainer and behaviorist for her, too!