What Causes Dizziness And Nausea?

Hi, I have lived in Bali for the last 3 years and ride a scooter all the time. I notice that this has affected my posture, and also gives me a very stiff neck and back, and my necks clicks and grinds all the time when I try to stretch and exercise it. I was in the bath this morning and threw my head back, to then feel an overwhelming pull in my neck/base of my skull. I managed to get out of the bath feeling very dizzy and nausea. Six hours later, I have been eating and drinking lots of water and lying down, but whenever stand up I feel dizzy, faint and nausea :-( What do I need to do?