Oldsmobile/Buick Repair: I have a 98 Oldsmobile Cutlass...., oldsmobile cutlass, personal mechanic

Question
I have a 98 Oldsmobile Cutlass.  Not sure of the engine size.  I noticed yesterday that the car was overheating.  I stopped and check the anti-freeze.  There was no anti-freeze in the car.  I filled it up.  Again this morning I checked and there was no anti-freeze.  I checked the oil and found that the oil looked like mud.  I just had the oil changed 1 week ago.  What could my problem be?  I just bought the car in February of this year.  It's been running fine.  The car was serviced in September by Lube 'n go and my personal mechanic changed the oil, because Lube 'n go used a light weight oil instead of high mileage oil.  So I believe what ever happened to my car happened just recently.  

Answer
hi cindy.well no sense sugarcoating things .you have major problems you are leaking antifreeze into the oil most likely head gasket if this started after a real cold spell cracked head or block get ready for some major eng repairs .sorry to have to tell you that .please rate my help ty billymac