I am a 23 year old female, U.S. born of Indian origin, petite, in second year of medicine. I was on the varsity tennis team in the high school, but did less physical activity in college. I used to get severe apthous ulcers of the oral cavity for a number of years and had all the required tests with no cause identified. I am an ovo-lacto-vegan (no fish, no poultry, no meat, dairy yes). I started med school (off shore / Caribbean) in May 2008, had high stress (academically as well as the location) in the first 2 semesters and have been excelling in studies since Jan. 09. Around Oct. 08, I started having bilateral knee and calf pains. When I came home in Dec. 08, I had a number tests including MRI of the knees to rule out meniscus tear, bilateral lower extremity venous study to rule out DVTs and blood work ups to rule out autoimmune disease. The results all came out to be negative and I was advised physiotherapy. I returned to school and remember falling down on Jan. 16, 09 with trembling knees and tight calf muscles and started having problems with walking, climbing up (weakness) and walking down (balance) the stairs, and started walking on the toes. If I was sitting on the ground, I could not get up without using my arms and upper body. I managed to keep going with my studies until April 09 (since I assumed that all problems were related to general weakness) without realizing the severity of the problem, lost my balance and tripped a couple of times. I came home on a two week semester break in mid April. Noticing the problems, my physician mother, made quick appointments with a Podiatrist (I used to wear flip flops on uneven / unpaved roads) and a neurologist. The podiatrist concluded that it is not connected to feet or back problems. Between the two, I had bilateral EMG, MRI of the brain, neck, thoracic lumbar and sacrum. Blood work included B12, copper, vitamin E, zinc level, ceruloplansmin, antibody to HTLV-1, blood for MS panel and CPK. The neurologist noticed leg spasticity, ankle clonus and hyper-active knee reflex. The sensory system examination showed no problem. I had a LP for sugar protein, cell count, MS panel (including CSF IGG index, Oligo clonal bands, Myelin basic protein) and cervico-thoracic myelogram, I also consulted with a Rhumatologist and the related blood work to rule out rhumatological issues. All results were negative. EMG was nonspecific except low conduction with the medial head of the calf muscle. Because of the test results, the neurologist suspected Hereditary SP and recommended that I consult an academic neurologist for second opinion. This neurologist found the same problems during physical examination and had me go through EMG again. Again no diagnosis of the underlying problem resulted and I decided to head back to start a new semester. 3 weeks later, I developed bilateral lumbar pain radiating to both scapula and came home for further examination. First I had a T10 to lumbar MRI to rule out complications related to LP and EMG and the results were negative. The specialist had a long neurological exam and felt that the weaknesses were progressing fast to upper extremities. He consulted with an expert in HSP in Ann Arbor and came out with the feeling that problem might not be related to HSP. He decided to have a high resolution MRI of cervico-thoracic area for spinal compression and entertained an AVM that was dropped with consultation with a neuro-radiologist. I ran out of time to do anything further immediately and returned to my studies with an idea of coming back in a month for re-evaluation. I continue to have the same leg related problems and use walking cane as needed. I get tolerable neck and back pains (perhaps due to the weakened muscles and poor spring mattresses) and use NSAID as needed. I would like to get proper diagnosis soon and have the required corrections before irreparable damage occurs. I am not in any medication now. Could all the problems be stress related since most results are negative Any suggestion on what might be missing in my diagnosis and the probable cause and solution would be really appreciated.