It shows that your chin has some mucus and gas. The mucus is probably from irritation (maybe from the medication?) and the gas is because the bacteria present in the intestinal tract are, well, putting off gas due to an imbalance or overpopulation of bacteria. Sometimes chins just have weird droppings that are just hard to explain.
One thing that would probably help out in a short time would be to give the chin some probiotic. Just get the capsules with the probiotic powder in them and sprinkle the powder right over the pellets. Whenever I see anything like this that's what I do to help bring things back into balance in the intestinal tract.