After 35 years of being a dentist I have found that if a tooth has sensitivity after a crown of deep filling, and after waiting six months, if there is still sensitivity, the sensitivity almost never goes away. Remember, pain is almost always a sign that something is wrong. In your case your crown was done over a year ago and you probably had an unhealthy nerve in the tooth to begin with and the crown procedure caused additional irritation and inflammation, and now the tooth's nerve has had more than it could cope with. I advise you see an endodontist (root canal specialist), who will test your tooth to determine the state of health the tooth nerve is in. If may be that you might need a root canal treatment to rid yourself of your sensitivity.