Growing up I had the same problem. It always happened after I had been laying down and would stand up. Sometimes it would just be a little dizziness and my skin would tingle. Other times it would be so severe my skin would be so tingly, my whole body would lose feeling, I would black out and fall to the floor and after a minute or so would wake back up. It was very scary for my family to witness. I'd be laying on the couch, stand up, go to take a step and fall to the floor and be unable to move and see only darkness. For a long time my mom thought it was something I was doing for attention. Finally, after I was diagnosed with mitral valve prolapse (heart defect) I happened to mention it to my doctor. I was told that its actually a fairly common thing - that what happens is that when you are laying down you are relaxed and calm and your heartbeat is slow and regular. Then when you move from a horizontal position straight into a vertical position, your blood pressure dramatically changes and in some people it takes your heart a few beats to adjust to the change in the pressure. While this is happening, the blood flow to your brain is temporarily lessoned and you become lightheaded and dizzy until your heart catches back up again (usually within seconds) and you feel normal again.
I have found that as soon as I feel the dizziness and lightheadedness coming on I immediately sit back down until it passes. When I feel that its going to be severe I have found that quickly sitting down and putting my head between my legs so that it is lower than my heart for a few seconds helps me from passing out. By doing that, you ease the strain on your heart as it tries to pump blood up your body into your brain. The whole experience is very strange but relatively harmless. The only thing you have to worry about is passing out and hitting your head on something. If when you feel it coming on, just sit down for a second and you should be fine. Hope this helps and makes you feel a bit better. If this is something that you say started only a few weeks ago, it might be possible that you do have some kind of iron deficiency that might be contributing to this (iron being whats in your blood that helps it carry oxygen). If it continues to be bothersome, go to your doctor and hopefully he or she will be able to ease your mind. Good luck!