For someone whose kidneys have shut down, removal of water is painless because the body won't dehydrate. Waste in the blood will accumulate to toxic levels, but adding water won't fix that and may cause problems of its own.
Similarly, if other organs shut down the body will stop being able to metabolize digested nutrients and consequently food intake is no longer needed to keep blood nutrient levels adequate. The lack of metabolism by-products to feed the rest of the body will be a problem, but adding non-metabolized food to the system won't fix that.
In other words, the removal of food and water can be painless, if the body has deteriorated to the point that it no longer consumes them. If the body has not deteriorated to that point, however, dehydration especially can be extremely painful. If the kidneys simply stopped working early on, it might not be quite so bad, but often the kidneys will continue to extract water even after the body's level of hydration has become critically and painfully low.
Just the first day, let alone the first several days, had to be painful. I cannot imagine hunger pains and thirst NOT being most uncomfortable and painful.