For the past month or so i have felt very nauseous. It used to happen only at night but now it happens a lot?

Now it happens a lot after i eat and can last all day. One day i couldnt take it anymore and went to the hospital. I had a biopsy done( i think thats what it is where the put a tube down your throat and look around in your stomach) and they saw nothing wrong. I also drank barium and had some xrays done but nothing was wrond and i had a sonography done and still nothing was wrong! I am a 20 year old male and cant take it anymore! I havnt ever thrown up from it but i always feel like im on the brink of it and the only thing that soothes the nausea is a hot bath. What is going on?