I went to a concert last night and ever since I have a sensation of one ear being blocked and ringing in that ear.

If you have never had ear problems before and are experiencing a plugged sensation and buzzing in one ear after attending a concert, it is possible that you are experiencing symptoms of an ear infection or blocked ear canal. If you are also experiencing systemic symptoms such as fever, congestion, or cough, it could indicate a sinus infection. It is advisable to take pain relievers such as Advil or Tylenol and monitor the situation for about a week. If the symptoms persist, it would be best to seek medical advice and have a consultation with a healthcare professional.