My girlfriend was experiencing symptoms of her period for about a week or two. she finally had what she believed was her period (light bleeding). we then had protected sex two days later. now four days later she is bleeding badly. what could this be. she

Irregular periods: Irregular periods are one of the most common problems obgyns treat. If this is one time problem it usually resolves on its own. If this is a recurring problem you should be evaluated. Infections and hormonal changes can cause spotting. If there is a concern for pregnancy then do a home pregnancy test . There are many options available to help regulate the menstrual cycle. Schedule a visit.