headlights and flashers are constantly flashing every time I open my doors

My headlights and flashers are constantly flashing every time I open my doors and stays flashing the whole time I'm driving. As long as my headlamps are on bright the headlights won't flash but flashers are still flashing after car is cut of about 15 min later the lights and flashers stop but soon as I open doors they start and do it the whole time I'm driving. What could this be and how can I fix it ? Please help me.