Hello, Your father has returned to the dentist to find out that area is healing well after the extraction, but has he had an exam and recent cleaning? I can assume the tooth was infected due to your description of pus, but do not know the general condition of his oral health. The infections affect the entire mouth and body. Please follow up with a full dental exam if your father has not completed this. If this does not resolve the condition, other systemic deficiencies or disease possibilities need to be considered. Correct diet, needed vitamins and keeping well hydrated are important. I have concerns with the quality of his saliva and adequate flow of saliva. His medications may cause dry mouth. The daily plaque will become thicker and more difficult to remove. Tartar will develope and this can feel rough. An infection that was draining may have created a coating and caused a higher acidic content in the mouth. If your father had been placed on antibiotics, this may disrupt the bacteria balance in his mouth. Sometimes an oral yeast infection can occur and need treatment. The tongue can become red, sore and have a different feel or texture. Thank you for your inquiry. I hope my response has been helpful. Please provide additional details if you would like me to provide more information and recommendations.