It is not normal to experience two menstrual periods within 2 weeks and is considered irregular bleeding. Irregular bleeding can be either organic or functional in nature. Organic vaginal bleeding can be due to conditions such as the presence of tumors (benign or malignant), infections, injuries etc. Functional bleeding from the vagina is frequently due to a hormonal disturbance in the endocrine axis of the hypothalamus-pituitary-ovaries. Such hormonal disturbances can happen while taking birth control pills. This side effect usually occurs when a woman begins birth control pills until the body can adapt to the hormones contained in the BC pill.