I would guess it drowned. In the future, pick up a potted plant before and after you water, and judge the weight. A dry plant will be much lighter than a wet one. Just try to pick up one side of the pot if it's too big to pick all the way up. It's just too easy to over water a plant. The fertilizer probably didn't cause the wilting.
Or did it start looking like this hours or a day after you got it into your house? Could have gotten too cold on the way home?
