I have a 3 year old shepherd with a very weak stomach. she gets car sick, randomly has accidents if left home alone. If we are home she will let us know that she has to go out. She has been eating Purina for the past couple years...over the past day or 2 she has had really bad diarrhea, the food is the same, could it be the food? she randomly has accidents, I just don't get it...does anyone have any ideas?