Is it normal to feel lightheaded and see green cloud things on your period?

Whenever I stand up I get waves that start from the outer part of my vision and move inwards and they look like greenish purple clouds and then they clear away and three seconds later they come back like in waves. I'm scared to walk in case I faint. When I was 7, I fainted and had similar feelings as I do now and I had to go to the ER but they never found out what was wrong. So is this something common and related to my period (I've also been having very bad cramps and nauseous feelings) or is there something wrong with me that needs medical attention? If so, why would I suddenly have this weird problem again 9 years later?