Mazda 6 warning lights

[jjfrisk]

while driving my 2004 mazda 6 wagon with auto transmission yesterday i felt a thump and instantly the warning lights for the auto transaxle, check engine and traction control came on. car had no power, would not rev more than about 1500 rpm, would not change gears with tiptronic. car has about 125000 miles. Went out to the car this morning and check engine light is still on but other lights are off. Please let me know where to check first and also if anyone else has had this happen. Fearing the worst how much will a transmission cost.

Thanks