I have no pain with my tremors either, but maybe your pain is from a combo of fibro, ET and your back issues. I sometimes wonder if my back issues are contributing to the ET, as it seems a lot of people have both. Just looking for a connection, I guess. I, like you have just started getting the jerking movements. I thought it was just restless leg syndrome, who knows?
A few weeks ago, I was making corn muffins. While spooning the batter into the muffin cups, my hand started jerking uncontrollably. DH noticed it and came over to help. He grabbed hold of my wrist thinking that would stop the jerking, but it didn't. He asked me if I was jerking the spoon deliberately to get the batter to drop. Nope, the hand was jerking on it's own and batter was splattered all over the muffin tin & work surface. DH then took over the task for me. Don't even try stirring a full pot, sometimes there will then be more ingredients on the stove than in the pot.......lol.