2004 Chrysler Pacifica Blown head gasket?

Engine Mechanical problem
2004 Chrysler Pacifica V8 All Wheel Drive 55000 miles

Help! I have a 2004 Chrysler Pacifica that just 2 months ago, on the car dealers recommendation when I brought the car in for inspection, I let them "clean" the throttle body/combustion chamber to the tune of $111.00. Today, out of the clear blue sky, my Pacifica makes this horrific clanging noise as I begin to drive, then going up hill. Sputters and then dies.

Others have told me it is probably a blown head gasket when I told them that the oil, when checked with the dip stick, was milky.

My question to you. Did this "cleaning" of the throttle body and combustion chamber have anything to do with my car's problems now?

I am car "illiterate" and want to have a leg to stand on when I take it back into the dealership before I am raked over the coals!

Thanks!