Could Dizziness And Nausea Be Due To Dehydration?

This has happened four times within a year. I get nauseated first thing in the morning. If I don t sit or lay down it get s worse. I feel like I m going to get sick then I pass out for only a couple of minutes. It slowly gets better through the day. But I m very tiered and when I eat I get the hiccups real bad. Sometimes I get dizzy on and off through the day. My doctor thinks I m dehydrated but don t agree.