Your celiac disease may have been present before your diagnosis of MS.  It is rarely tested for, yet is a very common inherited disease.  The protein in gluten has been directly linked to neurological damage in people with certain genes - many more than were originally thought.  MS is one of the autoimmune diseases associated with celiac disease.  You may be surprised by how much better you feel and how much you improve on a gluten-free diet.  The learning curve for this diet is steep but fast.  Once you become accustomed to it, it's not really a big deal to eat gluten free because there are now so many products available to help with the diet.  BTW, even if the biopsy for celiac disease is negative, this does not mean that you are not gluten intolerant or gluten sensitive and still would be much better off following the GF diet.