I know that feeling - I have had that feeling, lots. Feeling crappy and out of control of your life can really get you down. I got to a real low point and tried to commit suicide last year but I'm still here thanks to my husband and some amazing people.
I'm trying to say that there is hope. Not necessarily for a miracle cure (and I'm rubbish on knowledge of tests, treatments etc, sorry) but for life. Ms can be a bitch and can take stuff away but there is plenty that you can keep a grip on. There is so much more to life. I have needed to adjust but I haven't let go of my hopes, dreams, love and am finally seeing a positive future, whether I do it in this wheelchair or completely cured at some point. There is so much life to live and I have wasted too long grieving, not living.
I really really hope that I don't sound preachy, i'm just struggling to find the words cos there is nothing more irritating then someone telling you to buck up when you feel bad. Feel free to PM me if you want to talk.