Headlamp coes on with break pedal

As the topic says, just recently i've been having the warning indicator on the dash flashing when i depress the footbrake, i checked the break lamps and theyre working fine, tonite i pull onto the drive against the garage door and i see the side headlamp (nearside) flash on/

I know its probably a short circuit, but the electrics havent been touched ever.

Any help will be apprecaited.

Thx

Btw A6 2.5 tdi red i on the 98 plate :)