Hi Dear, Welcome to HCM. Understanding your concern. As per your query you have symptoms of pain in ear, upper jaw, headache while on low calorie diet. Well there can be many reasons for symptoms you mention in query , but in your case it seems to me that the symptoms are due to sore throat , sinusitis, it can be bacterial or viral . Also infection has traveled from sore throat to ear through Eustachian tube. But in your case the symptoms are probably due to sinusitis. I would suggest you to consult ENT specialist for proper examination . Doctor may order throat swab test and blood test along with examination with laryngoscope and otoscope . Doctor may prescribe antibactrial ( amoxicillin or penicillin ) , anti viral ( acyclovir ) along with anti allergic and decongestant . Sometimes low calorie diet make immunity low , so make sure that you are taking vitamin and mineral rich food . For now do warm saline gargles and take steam . Hope your concern has been resolved. Get Well Soon. Best Wishes, Dr. Harry Maheshwari