Juvenile parkinsonism?

At night sometimes I get spasms, they only last a few seconds and they're not bad or anything; just before I have it, I see the ground, and then it's almost as if I'm falling onto the ground, it kind of feels like I'm lifting my knees up. It's hard to explain. Anyway, my mum was watching a tv programme about dreams, and it was talking about REM sleep disorder, and how it can involve spasms, and also how it can be a symptom of Parkinson's disease. My grandfather had parkinson's for ten years, it was horrible, he got worse day by day by day, in the end he couldn't even open his mouth or walk, or move from his chair without istance from two carers. I'm thirteen and probably being really paranoid but is there a chance I have juvenile parkinsonism? I just need to know, I get extremely worried, it's silly really.