I've been injecting Betaseron 1b since 2002 and my disease has remained stable. I too started off with a numbish sensation down one side of my body. The docs say that these "sensory disturbances" with M.S. tend to have a better long term outcome so don't despair!
Wait and have a serious talk with a Neuro before you throw any baby out with the bath water as far as choosing a Disease Modifying Drug is concerned.
They only work in the beginning phases of M.S. so keep that in mind! The idea is to keep the disease in an early stage which is what these drugs try to do.
I have tolerated the shots well and so has my brother in law who has taken them for 16 years. I don't like taking shots, and my skin looks like a bruised mine field! But I feel well and have only incurred one new lesion on my brain since I began the shots.
You can also talk to the doc about the new pill for M.S., but it has far more possible side effects than the shots.
When I was diagnosed in 2002, my Neuro sugguested Betaseron (the first M.S. drug) and I trusted her judgement.