If you have a dental abscess
Your tooth might be hurting when you bite down because you have a dental abscess. A dental abscess [4] is a bacterial infection, where there is a build-up of pus. This infection can cause severe pain and make it difficult for you to eat. The pus or swelling inside your gum or tooth exerts pressure on your tooth, which causes pain when your chew or apply pressure on it.
You might be able to tell if you have a dental abscess, this is because the pain you feel is often reoccurring. Sometimes you don’t feel it, other times you feel worse. You may also notice some pimples on your gum, around the affected area. If you taste something salty, it is probably the pus, which indicates that you might have a dental abscess. Immediately visit your dentist for treatment.