Take a test or wait

I'm a week late but all week I've felt really nauseous. I've never felt like this with having irregular or late periods before. Should I take a test or wait a few weeks? Along with feeling nauseous my low back has been hurting and certain foods that I loved eating I can't stand the smell of or even look at without getting sick. I have been to the point of throwing up every few mornings. Water doesn't help and doesn't taste good it makes me even more nauseous.