What could be causing these jerky motions when I move in specific ways?

[GeneFeldman]

I've noticed that within the past week to two weeks, I tried lowering my hand down from a bent position and on the way down its like it hit turbulence, both arms. This happens when I reach out to grab something as well. It doesn't seem to happen when I do it very slowly or very quickly, just a controlled motion. This also seems to happen in my back or my abs if I bend over and back up again as well as in my shoulders.

Somethings I've noted is if I tax the muscle by going to burnout by curling a weight, this smooth motion returns but only for like 10 to 20 seconds. If I lift my arm straight out and bend my arm the same way, the turbulent motion is gone. It seems to be tied to certain positions that I'm in.

I had an MRI in early 2016 and that was negative.