This may all sound a bit mad but bear with me.
About 10 years ago I had a rash of very unpleasant symptoms including moderate loss of feeling/tremoring in my right arm (and to a lesser degree leg). I had a lot of high level tests - MRI scan, trips to Harley Street neurologist, with brain tumour, minor stroke and Ms being bandied around.
They all came up clear, but then no ongoing diagnosis - problem still persisted. Drs then all lost interest a bit and either said "not my area" or "probably a virus - go and lie in a darkened room and listed to whale music".
I then saw a very good private GP who diagnosed a respiratory/hyper-ventilation problem within about 3 mins of me going to see him. What he did not know was that I had had it diagnosed about 20 years previous to that (different symptoms). The doctor said that when level of gases in your blood is in such disarray, your body can go into a kind of shutdown of what it sees as its "luxury" systems - for me my right hand side.
Beta blockers were prescribed for me, plus seeing a specialist for breathing retraining - so if it is similar, the beta blockers should really help (I think the point is they slow down your autonomic functions, thus for me they slowed down my rate of respiration).