This same thing has been know to happen when spirited driving is done in the snow. assuming that you bent nothing First thing to do is make sure you wash all the mud out of the wheels. You may even want to take them off to do this. Try the car now. If it still shakes as you described. Get more invloved Check for more mud on any thing that rotates. This is the most likely problem and most inexpensive to correct. let us know what happens there are more thing to do but this is where to start