Maybe this will help...

When you laugh real hard you can cause insufficient blood flow to the brain so you which means that your brain is not receiving enough oxygen and will make you feel dizzy or even faint.

I have vertigo and I have problems such as this too. Maybe ask your doctor, this sounds serious!

Sounds like your body is in need of oxygen. Once you stop laughing, you start breathing again and are fine.

Wow. Thank you so much. I mentioned it to my doctor and she said as long as I don't actually pass out it's not a big concern.
That information is very helpful LindaZY. Thank you!