Yes 3 years are a long time that you are not serious about this problem. No pain doesn't mean everything is more or less alright.A cavity can spread extensively in the tooth as well as infect the surrounding gum and bone.

Hello, My dear friend, you are a young man you should know that like any other thing even our mouth needs periodic maintenance, so it will be a good idea to get the dental check ups done every 6 month and for your its high time. Any problem dental or medical is small in the initial stages and if you ignore it, it grows and become more stubborn. Don't ignore any health issue. Looks like you got a deep cavity involving the nerves. take care

U get an X-ray done .. according to d X-ray we can diagnose

Still u have not visited dentist and your msg in  phone