For over 2 years I have been experiencing nausea and vomiting almost daily, it is worst on the morning and is not related to the type of food I eat although it is made worse by eating.

I have had endoscopy which is clear no ulcers no reflux.
Helicobacter negative.

And the gastroenterologist are leaving me with no answers.

I am taking 40mg omeprazol twice a day. To no effect although causing side effect of diarrhoea.

What else,could possibly be causing my symptoms and what should I do now?