I am so sick of being sick?

the doctors have done blood tests for pretty much everything.. i even had an ultra sound done on my gall bladder.. they said nothing was wrong. everytime i eat something, my stomach feels so upset, the food just sits in my stomach until i throw it up, which isnt hard to do considering if i just push out a little i throw up.. i dont know whats wrong but im so tired of it.. does anyone have any ideas