This is highly likely natural thing (paralysis).it paralyzed me 2 or 3 times, as i was waking. i was able to quickly regain motor control and pray and banish it.
You body just slighty malfunctions. You see, during sleep body enters into paralysis so that you don't actually move during dream (easy to see why is that dangerous).
What should happen is paralysis stopping with waking up. Your body is just slighty late.
Also, have you checked natural causes with 2/3 doctors? It's possible it's supernatural cause, I would like to rule out natural causes.