It's Time, you are NOT alone.
I had probably the most severe GI illness/flu/food poisoning of my life in 2010. It left me with constant nausea and dizziness. The Dr. suspected my gallbladder was the problem, so out it came, but the nausea, and the feeling like I was on a boat all the time, stayed. I lost 25 lbs in 6 weeks because I was too nauseated to eat.
I was tested for celiac, H.Pylori, had an endoscopy, blood tests... and was finally diagnosed with IBS. I take Questran to control the D, which was a miracle for me after the gallbladder came out. Controlling the D was a huge help in controlling the nausea.
But still, I experience nausea (especially in the evenings) a few times a week. I am always nauseated if I'm having a D-day. Sometimes I will wake up at night with severe nausea and the urge to have a bm, the nausea generally fades after I've gone to the bathroom, but it can take an hour or so. If I have what I refer to as a "night poop", it always always comes with the horrible nausea.
I brought all this up with my gynecologist, who has historically been my most thoughtful and effective health care provider, and he suggested that my Vagus nerve might have been damaged during the awful vomiting sickness I had in 2010. I still don't know if that's really what the problem is. There's no test for it. He did say it would probably heal, but that nerves take a long time to heal - like years.
The good news is I am much better than I was - it has slowly been improving. The dizziness is rare now, I only get the "on a boat" feeling around my menstrual cycle and even then it's not every month.
However the nausea persists. I count myself lucky as I have no troubles with pain, but the nausea is exhausting and demoralizing. I too get some relief from anti-anxiety meds (Ativan), but only take a half dose a couple times a week because of its addictive nature.
This morning I began adding soluble fiber to my diet. Hopefully it helps, I've read good things about it. I also keep a lot of ginger gum on hand, and that helps with the nausea. I get it at CVS, the brand is Sea-band. Daily light exercise really helps too - I do a yoga or low impact aerobics DVD usually.
My issues continue to be a mystery, I try to work with and around them as best I can. I just wanted to you know I have had a similar experience to yours, and that you aren't alone.