Have you installed a new radio or anything electric that isnt stock, i had problems with my headlights staying on when i installed my radio because of the auto dimmer for the display being linked to the headlights also you may want to check the wiring you might have a short somwhere in between the fuse box(or relays) and the actual headlight if you cant think of anything else take it to a shop and heave em hook up a computer to it , theyll tell you whats wrong for a few bucks its usually worth it, if that fails
poke it with a stick lol