Feeling Nauseous, Dizzy, Light-headed For 4 Years

For a little over 4 years now I feel sick to the point of vomiting at least 4-5 days a week. I get very lightheaded and it sometimes gets to the point where it feels like the room is spinning. I have been to the Dr. more times than I could even begin to count and have had probably every test imaginable not once, but multiple times. Everything comes back normal. EKG, CT, Countless blood tests, Thyroid T3 and T4 have been checked, etc. etc. etc. etc. I have tried 3 different anti-nausea medications, tried cutting out gluten and dairy, and I really don't know what to do anymore. This sickness has overtaken my work and home life and no one can ever seem to give me a clear answer. Any help or suggestions would be greatly appreciated.