What Causes Nausea And Light Headedness While Standing Or Brisk Walking ?

I am experiencing nausea and light headed feeling. Especially when I stand or walk to fast. The car doesn t help either. This has been going on the past week. I started out with a bad stomach virus which began with pain and moved into nausea now. I am not pregnant so that s ruled out. Just finishing my period. So migraines were in the mix a few days. I had nausea so bad this morning I bought Dramamine. Fatigue as well.