Why Does My Head Spin After A Neck Injury?

When I was younger I fell on my head and messed up my neck. It's out of alignment and pinches the nerves at the top of the spine sometimes resulting in severe migraines. This happened to me yesterday morning, I got rid of the migraine but what was new is depending on how I move my head or the pressure on my neck. Everything starts spinning and I get nausea, I threw up twice from it yesterday. I slept almost all day yesterday and today and when I feel better I start to get up but everything starts spinning again.