Hi Sarah,
I get them too but mine are random, lasting for a few minutes here and there over a two or three day period.
I did have tremors for awhile that caused some major jerking that was mostly in the legs. Sometimes the head and arms would get involved. It was weird. I was put on a seizure med to control them but, I'm not taking it now and no problems lately.
Sorry, I don't know the answer either. Like Ginny said, just one of those things. Hope you get some relief soon. Take care and you will be in my thoughts and prayers.
Babs