Necrotic tooth

[Melbell8]

I have a canine that is almost completely necrotic. It has only recently begun causing me pain and sometimes I can feel it in my sinuses and throughout my head. I am going to schedule a root canal, but lately I noticed the tooth right next to it is extremely hypersensitive to anything cold...especially near the gum line. Even air.
Is it normal for a necrotic tooth to cause this type of sensitivity to neighboring teeth? Is there a risk of pulpitis to the teeth next to the necrotic tooth the longer I wait to treat?

 

[honestdoc]

How do you know the tooth is necrotic? Was it diagnosed by a dentist? If the tooth is necrotic, it won't infect or cause pulpitis on the adjacent teeth unless the adjacent teeth has an existing problem. Feeling sensitive near the gum line may indicate exposed roots or dentin/cementum such as receding gums and/or abrasion or abfraction. Please provide x-rays and images of the teeth involved.