I was diagnosed with MS in 2008 and I was 26 just turning 27. Like you I had the numbness which started in my face and neck then went on to my whole body. Before I started the meds my consultant showed me my MRI scan and sometimes I think medical professionals forget that we cant always understand these things. When I saw my MRI scan I couldnt see anything on it, except a "shadow" patch on my brain (at that time i was just glad a brain showed up LOL), but on my spine was a small Lesion which I couldnt see, thankfully my mum was with me and she asked him to explain a bit more for me, which he did and I understood it a bit better.
I think not knowing and understanding is the worst part and I agree with Gretchen i think you should ask your doc to give you a better understanding and hopefully it will help you out. I have been on Rebif for over a year now and so far it has been good for me, although my MS nurse did explain to me that not all meds would work just trial and error.
I have found that my diet effects how I feel also, like if I have spicy food I feel unwell and get tingling in my hands so again its trial and error with that too. I am still learning about my ilness and like chuck said there is alot of great people here who help as much as they can. Keep your chin up!!!
I hope you get the answers you need right now soon