Women's Health question?

Ok, so I am working with a nutritionist, and I have lost 47 lbs in 18 wks..That threw my periods off. But now I am back on semi-schedule, albeit no where near my old schedule was. Just got my period, and I have never experienced light headedness, pain, cramping, etc this bad. Nausea too. I stayed home today because it was so bad- that has NEVER happened to me before. Any correlation to the diet and the intense reaction to my period?