For the last five days or so I've experienced frequent nausea when I lay down at night. At first I attributed it to a late period, like my family has said, but I've always had late and rather infrequent periods and never felt nauseous. Along with nausea I get excessive mouth watering, feeling like I need to spit a lot, and feeling like there's a bunch of saliva or other thick liquid in my throat. Today the nausea lasted longer and has been bothering me. I took some anti-nausea meds to see if they'd work and they didn't. A part of me is concerned since my period has never caused this and I'm wondering if it could be something else. Could a period really cause this when it never has before? Or could it be something else?