Cavities / rotting of teeth is a destructive leasion that only get worse if untreated. There's no way to avoid or shun seeing a dentist as it would make it worse for you, Kindly visit your dentist and get it fixed so that timely care can be provided and to avoid spread to other aread. Timely action could also help in saving the tooth. In order to prevent recurrence and to avoid in future, ask your dentist about preventing cavities in future and go fot 6 monthly checkup visits.