Maybe be due to cavities, decay...you have to consult nearest dentist for further help as we can't prescribe medication as per law... Fallow bellow advices to maintain good oral hygiene
Good oral and dental hygiene can help you avoid cavities and tooth decay. Below are some tips to help prevent cavities. Ask your dentist which tips are best for you.
Brush with fluoride toothpaste after eating or drinking. Brush your teeth at least twice a day and ideally after every meal, using fluoride-containing toothpaste. To clean between your teeth, floss or use an interdental cleaner. If you can't brush after eating, at least try to rinse your mouth with water. If you have a young child, ask the dentist how much fluoride toothpaste to put on your child's toothbrush so your child gets the cavity-fighting benefits without getting too much fluoride.
Rinse your mouth. If your dentist feels you have a high risk of developing cavities, he or she may recommend that you use a mouth rinse with fluoride.
Visit your dentist regularly. Get professional teeth cleanings and regular oral exams, which can help prevent problems or spot them early. Your dentist can recommend a schedule that's best for you.
Consider dental sealants. A sealant is a protective plastic coating that's applied to the chewing surface of back teeth, sealing off the grooves and crannies that tend to collect food. The sealant protects tooth enamel from plaque and acid. Sealants can help both children and adults.The Centers for Disease Control and Prevention recommends sealants for all school-age children. Sealants last up to 10 years before they need to be replaced, though they need to be checked regularly to ensure they're still intact.
Drink some tap water. Most public water supplies have added fluoride, which has helped decrease tooth decay significantly. If you drink only bottled water that doesn't contain fluoride, you'll miss out on fluoride benefits.
Avoid frequent snacking and sipping. Whenever you eat or drink beverages other than water, you help your mouth bacteria create acids that can destroy your tooth enamel. If you snack or drink throughout the day, your teeth are under constant attack.
Eat tooth-healthy foods. Some foods and beverages are better for your teeth than others. Avoid foods that get stuck in grooves and pits of your teeth for long periods, such as chips, candy or cookies, or brush soon after eating them. However, foods such as fresh fruits and vegetables increase saliva flow, and unsweetened coffee, tea and sugar-free gum help wash away food particles.
Consider fluoride treatments. Your dentist may recommend periodic fluoride treatments, especially if you aren't getting enough fluoride through fluoridated drinking water and other sources.
Ask about antibacterial treatments. If you're especially vulnerable to tooth decay — for example, because of a medical condition — your dentist may recommend special antibacterial mouth rinses or other treatments to help cut down on harmful bacteria in your mouth.