Diahrea and constant nausea morning sickness?

For three days now I've had constant nausea (which was the sign of my first pregnancy). And most food is unbearable. I can't eat because sight and smell make my appetite run for the hills. No fever. No other symptoms. We have been trying , I'm wondering if I should take a pregnancy test? Or is it most likely just a bug? I've never felt like this before except the last time I had morning sickness. But I don't remember having diahrea last time.