Nausea/weird taste in mouth

Hey all, I'm due for af in two days but for the past three days I've been really nauseous. Not to where I've gotten sick but I keep getting that salivating feeling that you get right before you do. I feel better AS I'm eating, then right after back to nauseous. I also have a weird taste in my mouth but it's not "metallic" as they say with pregnancy. Just sour or something. Never had this before and I have two children. I don't know if it's some new pms symptom I've developed. Anyone thoughts?