With my 6th baby once I hit 30 weeks I started waking up feeling sick again and coming close to throwing up frequently. I had not experienced this before and thought it odd. I know some people never get rid of morning sickness, but for it to come back I thought was odd. But apparently not! There is no explanation for it, it just happens to some people, and with my 6th and now with the 7th I have developed it again.
I continue to take B6, which is supposed to help. It does not seem to make much difference for the third trimester, in my experience. Honestly, I have found that eating something high in protein and good carb as soon as you can helps more than anything. I've never needed any medicines like I sometimes do in the first trimester. I think it may simply be the body craving a little extra nutrients to finish out the pregnancy strong, but again we do not really know why this happens.
Have you experienced third trimester nausea? What helps you?