I think the advice to go see a doc is a good recommendation. Your symptoms are worth looking into. Mild cerebral palsy is a possibility. Or some other sort of neurological problem could cause those symptoms, A condition called dystonia is very common. That just causes stiffness and dysfunction, usually in a limb or part of a limb, when people move. Some types of dystonia are strongly genetically linked, but the part that doesn't add up with your symptoms is the mouth involvement. Also, dystonia often comes on later than the teenage years.

Definitely go talk to your doctor and see what might be causing that. If you had a little vascular malformation in your brain or perhaps a slight electrical disturbance up there that's interfering with the signal between your brain and your legs and mouth, you'd want to know about that sooner rather than later.