progrssive ascending unilateral weakness

I am a 26 year old female and began having symptoms almost 3 years ago. I have changed from a 5/5 muscle strength on my left side to a 3/5 on my good days. My weakness started off as activity related beginning with flaccid ankle eversion after intense sports. Slowly, the weakness is occurring in all ankle directions, knee extension, and all hip motions. I now have to wear an AFO for ambulation and some days I cannot even move my left leg at all and have to use crutches. My symptoms are still aggravated by activity, but my activity has been downgraded from an hour of vigorous activity a day to basic ADLs because I do not have the strength to do anything else. I have been to multiple doctors including 2 neurologists. I have had MRIs of the brain, and entire spine, NCV/EMG, blood work, and doppler studies all negative.

My last doctor felt strongly that I needed to be seen at Mayo Clinic to diagnose this mystery and today I got a letter saying they denied my request for an appointment.

Please help me with advice or insight.