Yup, stinky bum is gone so long as I don't change his food. My vet isn't entirely sure why the food change worked, I'm just glad it did. We put him onto Medi Cal Hypoallergenic HP.
I couldn't say whether a food change could help you, but it's another option
If it is discharge from the anal gland it isn't harmful to ingest. Your vet will be able to access what is going on back there and help you figure out the best way to tackle the issue. Good luck!
"He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion."