Why do I get dizzy during my period

Ok am 16 years old and usually 1 day or 2 day before my period I faint or get dizzy.
I remember few days ago I was taking a shower and just suddenly it got really noisy like a loud bell sound that I only could hear few seconds after that every thing was spinning and my vision was blurry. I don't know what is happening to me. I told my mother, we went to our doctor and stuff but everything came out normal. I really don't know what to do it's like I can't do anything during my period because I will pass out. Please help!