Persistent tooth sensitivity after flap surgery may be due to exposed root surfaces or delayed healing, but it usually improves gradually with proper care. If it continues despite desensitising treatments, a review by your dentist is needed to check for nerve irritation, incomplete healing or underlying dental issues. The neck spasms are more likely due to muscle strain or referred pain rather than a primary neurological problem, especially with a normal X-ray. You should follow up with both your dentist and, if symptoms persist, consult a physician or neurologist for a more detailed assessment.