There is just not enough information to say what is causing the numbness. Since the reflexes are decreased on the side with the numbness, I would suspect a periperal neuropathy (disorder of the nerves). This would not be consistent with MS.
Decreased reflexes can be seen with MS, but far and away the more common is increased reflexes.
You need to see your regular doctor and probably be referred to a neurologist. One of the studies that might be useful is an Electro-Myogram (EMG) and Nerve Conduction Studies.
At this point it does not sound much like MS though no one can diagnose or rule out anything online. But it does sound very uncomfortable.
Keep us posted.
Quix
At this point it's hard to say what's causing your numbness, but it could be caused by any number of things. Usually it's damage or compression of the spinal cord or the nerves coming from the spinal cord.