More likely there's a hairline fracture in the tooth or a small cavity all the way through the dentin to the root. Do you notice it more often with cold or hot? Sweets? All the time? Keep in mind it could also be transferred pain from your sinuses or another problem. Sinus issues would not normally last a year though. On a scale of 1 to 10, 10 being unbearable, how bad is the pain?