So sorry that you are going through this. I hope that you can find something to help her. When my mare was diagnosed with EPM I was heartbroken. She had off and on lameness, some days she was a ok and others I could feel something was not right. I was about 13 during this time and it was hard. I remember that I had to let my stepbrother and his friend borrow my horses for a ride one day and Annie came back cantering on 3 legs, one rear off the ground and he didn't eve know the difference! I was so upset and angry, needless to say he never was allowed to borrow them again. She was seen by many vets and we got all kinds of different things they thought were wrong with her. Finally we found a good vet. Her symtoms, off and on lameness in the right rear - always this leg it never traveled, she did have the droopy lip, and one day she has a sore back, very slow eater, loss of muscle tone on the right rear hip. After one month on the meds and lunging every other day - 10 minutes walk and trot both sides and built up from there, she was a totally different horse. 3 months of treatment and work outs and she had a new lease on life. When she was 17 she outdid the 6 y/o on mtn rides. We never did do the spinal test, we did blood and went by symptoms. Best of luck to you and your girl.