Stabbing pain right back upper throat, periodically. red place there. also bottom very back molar has smelly pus when rubbed sometimes on same side?

See a dentist: Without seeing the tooth and having an x-ray makes it difficult to diagnose. I would suspect that the molar is infected. Most likely a periodontal (gum issue) or that the tooth is abscessed and may need a root canal.

Pus : exuding from the infected site goes into the system every time you swallow. Retained third molar impaction, posterior decay, and gum disease, are possible source of infection. See a dentist ASAP.

Wisdom tooth ?: From your explanation that is what it appears to be. Most probably infected. May have a large cavity.... those teeth are very hard to keep clean. Please see your dentist ASAP. An infection in that area can quickly turn deadly if the swelling closes off your airway. All the best...