I was driving down the highway nicely (no problems at all before this) and a bump sounded under the car. I did not hit anything but the next day it started shaking, having trouble going uphill without being put in D2 or Low (something I have never done before), and seems to want to cut off when I am stopped although it has not done it yet.

I had just had the oil changed and the tires rotated and told that the belts were fine, etc.

Can you help?