Unknown reason of nausea

For like a month now straight I been feeling very nauseous throughout each day and it's affecting me a lot to where I barely even eat or can stand to eat because when I get to trying I feel like I'm going to throw up I took a home pregnancy test it was negative the doctors set a urine one for me and it also was negative I don't know what to do but this is bothering very much I even had to leave work because I felt like throwing up and was dizzy... The doctors didn't even do a thing but had me pee in a cup😫 any ideas anyone?