I am so sorry you're going through this. We had a 3 month ordeal with a friend's mare being suspected of EPM. After multiple negative tests it was determined that they believe hers was actually a flexor injury coupled with some chiropractic trouble (possibly kissing spine, etc). She's still in physical therapy. I doubt she'll ever fully recover.
It was very, very scary with her being pastured with my horses. I didn't know what EPM was, and they even suspected West Nile. So I held my breath for months hoping nothing would come up in my horses too.
It's in the 100's here now and our horses are dragging around too. I go out and spray them down with the water hose for relief. Maybe that would make her feel better and she'd perk up a bit?
Riding: The art of keeping a horse between you and the ground.