Can you have a movement disorder that only affects you when you try to use your muscles (like walking)?

Can you have one that affects you though your reflexes are fine? Doctors have yet to dx me with a movement disorder, because of my reflexes appearing fine.
But yet, when I try to relax my muscles (like in bed) my legs/ arms/ body thrusts itself a bit... lil' confused on all of this because though I have researched lots on RSD I haven't read up on too much about movement disorders.


P.S. Sites/ articles/ studies would be appreciated