Unusually nauseous

The past couple nights I go to bed and suddenly feel very queasy and nauseous. It comes on and off though, even if I've eaten. Yesterday I felt it during work as well. I have not been vomiting and I don't feel any other sickness other than this, so I'm wondering if this could be a pregnancy sign. I never ever feel nausea unless I take my medication on an empty stomach which I rarely do. No particular change in my diet or lifestyle recently. I just find this symptom very odd for me. I'd appreciate any responses, thanks.