[WaysletlyLene]

Ive had something like this

It comes on very suddenly & is pretty much motion sickness

In my case Id had a cold and my mucal membranes were gunking up my inner ears

One intresting technique i was advised on (and you should check with your doctor before trying this !!)

Hold your nostrils shut and try to blow into them - in effect youyre driving the gunk out of your ear/nasal passage

its pretty unpleasant though ! (it did help me)