I am experiencing a tooth ache & bitter taste. My neck & ear ache as well. If this is a tooth abscess, is it an emergency?

Dental emergency. It sure sounds like a dental emergency. Get to a dentist as soon as possible for treatment of the tooth along with antibiotics if there is an infection, which is likely. Infections can spread and cause serious consequences so do not delay!
Abscess. The problem is not an emergency, but it doe need to be addressed. Do you have a dentist? It would best to see a dentist as soon as possible.