The possible causes of your pain may be due to several factors.
1) Healing : Did the extraction socket heal properly? If not you might have a condition called Dry Socket which is painful and may cause irritation. it is caused due to delayed healing, no proper maintenance of oral hygiene after extraction, or consumption of alcohol or tobacco after surgical procedure
2) Periodontal status of the adjacent tooth
3) The adjacent tooth might be carious
4) Local irritating factors
Next Steps
Consult your Dental Surgeon for a proper evaluation of the area where sensitivity or discomfort is taking place