You need to see a podiatrist. This specialty is often looked down upon by the M.D.'s, and they are reluctant to give a referral, but in my opinion they sure know a lot about everything connected with the foot.
3 years? You should have seen a medical person about his a long time ago.
Make an appointment to see your doctor to assess this foot.
You require the appropriate treatment and any medication.
Don't wait any longer and book the appointment and get is sorted out urgently.