Hello, Thank you for your question. Recurrence sore throat and fever can result from a variety of conditions. Cause can be from Allergies: when you have an allergy, your immune system is hyper reactive to certain substance that are normally harmless we call allergens. There are include foods, plants, pets, dust, and pollen. These allergen cause postnasal drip, excess mucus drains from your sinuses into the back of your throat. This can lead to sore, and scratch throat but no fever. Cause from tonsilitis most often is diagnosed in children, but people can get it at any age. It can cause by bacterial infection or viruses. Tonsilitis may recur adn requires treatment with prescription antibiotic if the working diagnosis are belong to bacterial infection. The symptom of bacterial infection are sore throat and fever with lympadenopathy and pus in the tonsil. If your grandson get recurrence strep throat more than 6 times a year surgery to removed tonsil is indicated to prevent from heart valvular disease in the future. How old your grandson is? Does he have runny nose, coughing, eye itchy, sneezing? If he has these symptoms he is more allergic or viral infection. But if he hs bacterial sign he should visit his doctor to make sure get the real diagnosis and treatment. I am I answer your question. Regards, Dr. Raksmey