I am healthy 29 year old stay-at-home mom of two small boys. For past month I ve experienced light-headedness for no apparent reason, it comes and goes right away, first time I felt dizzy I almost lost balance and held onto dresser; other times have been light dizziness , sometimes feeling a LITTLE nauseous. Has happened about 3-4 times week. I took a pregnancy test (off-shelf test, and it was negative). Today, I bent down to pick something up, and a shadow on PHERIPHERAL vision of left eye appeared--it took about five minutes for the shadow pheripheral area to disappear, felt a little nauseous also. What could be problem?