So I have had this 03 cts 3.2 with 133,000 miles for 2 months, tonight I was driving it and it got hot so I pulled over and shut it off I got out to look under the hood and a milky color fluid was dumping out of the coolant overflow tank I opened the oil fill cap and the same fluid was on the cap I just got an oil change 14 days ago so I got it towed to my macanic. what is going on!!!!