The cause of pain due to wisdom tooth is its malposition. Which leads to the gum coming in between the upper n lower teeth. Initially there is inflammation of the gum n then subsequent infection. When this happens there will be constant pain and then it's aggrevated while trying to close the mouth. sometimes it's associated with swelling of the cheek. And as it is malposed and causing all these problems its better to remove it.

Wisdom tooth is the 3 rd molar which is generally not of very much use in occlusion and if it is impacted or pericoronitis occurs it pains a lot. If you have already taken medicines by doctor's advise and still it pains then better to do extraction of this tooth than to keep it. First visit a dentist and have a X-ray done of this tooth. Then proceed as per dentist's advise.  For any more suggestion contact me at docs.animesh @gmail.com .Thanks