48 yr. old female diagnosed with probable MS 1 1/2 yrs. ago by neurologist. Also being treated for ulcerative colitis which started about 5 years ago. Have had full MRI of spine with no problems found. Have had ANA, rheumatoid, B12, etc. testing all negative. Neurologist is puzzled by constant, both legs with +1 knee reflexes. What could be the cause? Thank you.