Feeling lightheaded and mild nausea?

About 3 days before my period I began to feel lightheaded and mildly nauseated. I have never felt this way before. 2 preg. tests were negative. I started my period 3 days later and have felt this way periodically throughout the day every day. This is officially the 4th day of feeling like this. I have never had these symptoms before while on my period. I thought maybe I was a little anemic so I have taken a multivit. for two days and it didn't help. Any suggestions. The first day I felt like this was the worst. I also had a feeling like the room was spinning while my eyes were closed. No tinitis though. It felt like I really needed to focus hard to see things, even though there was no blurryness or other visual disturbances. This only happened once on the first day I started ecperiencing symptoms.