What does it mean to have negative pressure in your ears?

It means that the pressure inside your ear is lower than atmospheric pressure. It's not actually a negative pressure, but it is a way of saying "lower pressure than atmospheric" succinctly.

It means that the pressure inside your ear is lower than atmospheric pressure. It's not actually a negative pressure, but it is a way of saying "lower pressure than atmospheric" succinctly.
What does negative pressure lead to? My 5-year old diabetic son has this condition, is there any type of cure or anything I can do?

I don't know very much about this.

You could ask you doctor to have a look at this:

What is the EarPopper™? (http://www.earpopper.com/earpopper/index.htm)