My Daughter Is 34 Yrs Old. For The Past 3

My Daughter is 34 yrs old. For the past 3 yrs. her physical mobility has been decreasing. She originally had 2 jobs and was very active. After several MRI's there is no evidence of any spinal degeneration or anything else physically wrong with her. The only thing they can come with that it maybe "might be cerebellar brain atrophy. They told us to seek other professional help. What kind of Doctor should we see? Who can help us? It has been a 3 yr. battle getting answers.