What would cause two periods in the same month, low estrogen or low progesterone?

Vaginal bleeding: Your extra "period" might have been menstruation, but not necessarily; perhaps an episode of non-menstrual vaginal bleeding. As you suggest, it could be an estrogen/progestin imbalance, but infections and other causes also are possible. Any new or unexplained vaginal bleeding should be professionally evaluated. The safe plan is to contact your doctor and follow her advice. Good luck!