Why does my body shake when I lean up from laying down? LETS PLAY DOCTOR

[Star]

For some odd reason when I lay down and start to lean up, at one point my body starts shaking uncontrollably for some odd reason(not to the point where I can't finish up but still, it's odd). And I also noticed that when I lay on my side, my body will shake as well. A nurse once told me she thought it was because of lack of vitamins or something, so I started taking a multi-vitamin pill every morning. I still have the shakes though and I can't think of any other reason this could be happening. My back is quite sore sometimes so maybe it has to do with my back. I tried to look for other solutions and I can't find any. I think it may be a simple solution..reason why I'm asking before I starting thinking about getting a checkup..

Thank y'all so much for always helping me out.