Please check out Functional Neurological Disorder FND.

It’s what I have. There are no tests that show it because it’s not a physical condition.
It is described as a “software” issue between your brain and body.
Stressful times make it so much worse. I get tremors, my speech changes, my muscles will “freeze” in place.
They send you for physical therapy, and a psychologist to ease the symptoms.

I was diagnosed by a neurologist who specializes in Movement Disorders.