1993 GMC Suburban Head Lights

I was driving home last night when the head lights started flashing from high to low with out touching anything. Is this just the light switch or is it in the colum with the high beams. We have had the suburban for over 6 years and have never had any problems until now. The switch is not stable it move when you turn on the light. Please help as soon as possible as this is our only means of transportation and I drive 35 miles one way to work and we have about 2 foot of snow now so have to have head lights.