You need to take him to the Vet. Some times assumption can prove very dangerous. Whenever, you notice anything unsual in your dog's daily routine, you must consult a Vet. Don't assume anything as this can deteriorate the condition further. Regarding, yellow urine, keep a check on water intake by your dog. Lack of water intake can cause yellow and stinking urine. Always keep fresh water available all time.
Also home-made remedies can prove helpful on humans not on our animals. They can't tell you if it's helping them or not. Consulting a vet is the most sensible thing.