Welcome to health care magic!
After reading your question there are following important things- you have pain at back of neck while laughing, which means on bending head backwards or forwards, you have
migraine, and suffer from
vertigo and lightheaded ness while lying down. Your CAT scan is normal.
From my experience, I think that you might be having
cervical spondylosis. Had I been treating you, I would advice an
X ray neck, AP and Lateral view, and sitting and lying down Blood pressure readings, to make things more clear.
For the time, I think that avoiding any kind of sudden neck movements in any direction and bending down will help in controlling the episodes of pain and vertigo.
If you are working on computers for long time, taking a break of three to five minutes and looking around from the screen will give your neck a desired rest. Same goes with TV.
Avoiding big pillows while sleeping is also found to be effective.
Neck exercises are also very useful in treating this condition and preventing new attacks.
I hope this helps you.
Please feel free to ask more on this.
Dr. Manisha Gopal