The sores being located only on your tongue produce foul odor due to the cell degradation that occur in the sores. The inflammation that accompanies the condition increases the intensity of the odor. What you need to do is to solve the sores issue. You might want to visit your dentist to check for some chronic infection in your mouth. He might want to take a swab from your mouth and the sores and prescribe you some antibiotics and antiseptic oral solution.