You need to consult with Dentist take an x-ray and confirm whether there is any root piece remaining, if not take an antibiotic course, then it might be normal, the pain might be due to bone formation... Usually there will be some kind of discomfort for atleast 3 months after extraction of wisdom tooth until the bone is formed completely...
Next Steps
Have a consult and check with the x-ray...
Health Tips
See to that you don't bite any hard substances like bone on the tooth which is adjacent to your extracted wisdom...