Fear agression

[Magnolia]

I too have a reactive dog with other dogs. She was a stray rescue that came to me at 9 months. She is a 45 lb lab mix. Maybe a sheltie or some herding dog style. I have done obedience training and she enjoys backyard agility and she also went to doggie daycare one day a week for socialization until she was 2 1/2. When she totally lost her meet and greet skiills and developed a fear agression to other dogs. She always prefered playing with the little dogs and didn't like the big dog yard and that was fine and she was allowed to stay in the little dog area even tho she was bigger than all of them. She started to display the fear agression at 2 1/2 and is in the mode of "I'll get you before you get me" and starts a fight. Honestly the other dogs do not promote it at all. they approch her and are friendly and happy and try to 'get to know her' and now she attacks and she never use to. I have two other dogs at home that she gets along fine with and she is still fine whith all the family dogs that she met prior to 2 1/2. I would like to desensitive her so she can find another way to deal with her fear because when she attacks she usually gets clobbered by the other dog. I took her out of doggie daycare on the second incident. I thought maybe the first one she was just having a bad day. IF another dog while walking walks close to her she tries to snip them especially if they are a bigger dog. any suggestions.