I have a missing teeth on the upper right behind. it doesn't hurt but after a week, i feel a discomfort. the corner of my jaw looks swollen. what should i do?

Unfortunately : Unable to render a diagnosis without an exam and x-ray of the area. Obviously something that needs to be looked at asap by a dentist - swelling is not normal and quite possibly denotes an infection of some sort. Please consult with a dentist asap. Hope this helps.

Dental exam: Anytime there is swelling there is a concern about an infection. You should see a dentist and have this area evaluated and treat the problem. It is not possible to give you an answer here. You need an exam.

See your dentist...: It is possible you may have an infection. There may be other problems as well. I am having a difficult time figuring what exactly is going on based on your description. However, it does seem several problems exist. Please do visit a dentist.