Hi! Welcome to Healthcaremagic. I read your query. If the filling hurt you so much, I wonder why it wasn t taken out. It appears may be filling was quiet deep and close to the pulp. over the years it caused irritation to pulp and infection. Also, any overhanging filling can also impinge into gums. I suggest you to visit a dentist and get x-ray of tooth done. According to tooth condition and infection, it may need RCT or extraction. Get a prescription of antibiotics and painkiller from dentist and take it. Do warm saline rinses. Maintain oral hygiene. Take healthy diet, multivitamin and mineral tablet one per day. Avoid spicy and acidic foods till treatment is over. Hope the answer helps you. Thank you!