I would stop the charcoal and try Prozyme. I have a sheltie that has a sensitive digestive system and he used to have loose/soft stools up until the age 9 months when I discovered Prozyme. Once I started him on Prozyme his stools became very firm and consistent in two day...seriously it worked that fast. He still takes it and I have my older cats on it too and it's made a tremendous improvement in all their lives in regards to their health. Try googling it and research it yourself...I have personally experienced many of their claims to the product and highly recommend it. No I do not sell the stuff...just a believer in it after trying to solve my shelties digestive issues for such a long time.