welcome to the forum, sophie
i personally do not take DMDs, and the only book i've read on ms doesn't really fit with my current approach so i won't recommend it (although it is on the book list in the reading forum)
if you are interested in ruling out any nutritional issues that are known to be present in the average ms patient, i can help you with that side of things.
i had a look at reasons for balance issues, found this on wikipedia:http://en.wikipedia.org/wiki/Balance_disorder
Related to the brain and central nervous system
Brain related causes are less commonly associated with isolated vertigo and nystagmus but can still produce signs and symptoms, which mimic peripheral causes. Disequilibrium is often a prominent feature.
Degenerative: age related decline in balance function
Infectious: meningitis, encephalitis, epidural abscess, syphilis
Circulatory: cerebral or cerebellar ischemia or hypoperfusion, stroke, lateral medullary syndrome (Wallenberg's syndrome)
Autoimmune: Cogan syndrome
Structural: Arnold-Chiari malformation, hydrocephalus
Systemic: multiple sclerosis, Parkinson's disease
Vitamin deficiency: Vitamin B12 deficiency
CNS or posterior neoplasms, benign or malignant
Other - There are a host of other causes of dizziness not related to the ear. Mal de debarquement is rare disorder of imbalance caused by being on board a ship. Patients suffering from this condition experience seasickness even when they get off the ship.
Motion sickness - a conflict between the input from the various systems involved in balance causes an unpleasant sensation. For this reason, looking out of the window of a moving car is much more pleasant than looking inside the vehicle.
Toxins, drugs, medications
most items on the list above have a zinc nutrition connection, even b12 deficiency. a b12 problem could be related to the spinal lesions, not sure about the brain ones, though (although i can recall at least one case study documenting brain lesions in b12 deficiency).
last time i had vision problems related to zinc deficiency, i didn't have my optic nerves checked, i just felt like i could see everything perfectly, but couldn't make sense of it. it was hard to drive because i couldn't relate what i saw, to the passage of time. so it was very difficult to tell if it was safe to cross an intersection, or change lanes on the highway. i did end up asking for a zinc test based on the reading i was doing at the time. i got my first serum zinc test, and it came back 8.6 umol/L, markedly deficient. when i corrected the zinc level, my vision issues resolved and have not returned. zinc is very important for the eye - the eye has a very high zinc concentration, and zinc is required for the body to utilize vitamin a (retinol).
Zinc and the eyehttp://www.ncbi.nlm.nih.gov/pubmed/11349933
Nutritional effects of zinc on ocular and systemic physiologyhttp://www.ncbi.nlm.nih.gov/pubmed/6454715
"High concentrations of zinc are found in human ocular tissues and are closely related to visual function. When zinc levels are inappropriately low, results can include ocular birth defects, reduced ability to dark adapt, excessively low IOP, and optic neuritis."
if you want to read more about the nutrition approach from my personal perspective, here's a link: regimens-f22/topic2489.html
other than that there's lots of info in the diet and natural approach sections.