nauseous and faint

I'm currently 13w 4d and nausea is still persisting but Im starting to feel weak and light headed at the same time. Is this normal? I know both of those things are common symptoms during pregnancy but it seems to be getting worse - to the point of me shaking from feeling so weak. I am eating but can't seem to keep food down all that well, at least not in the morning. Bub was healthy on my 13 week scan and actually measuring big. Help? Advice?