What Causes Weakness In The Legs While Suffering From Multiple Sclerosis?

I have recently been diagnosed with MS. I was also diagnosed in 2003 and was never on medication. I started having weakness in my legs and had 2 MRI s. One of the brain but the MS Specialist said the location did not dictate the weakness in legs. He ordered and MRI of spine and one lesion was found in the neck. He put me on Glatopa but I had severe reactions not only in the swelling but also welts that did not go away soon. He took me off of the and now Rx is for Avinex. Still waiting to get. My family is very concerned and feels that there should have been some testing on vitamin B12 deficiency. I m not one to take a lot of medication if not necessary. I am on Symbacort and Omeprazole. I m just a bit confused. Thank you.