This is a very common finding, no specific followup is required for a 2 mm colloid cyst. If the thyroid ultrasound is this normal, the neck pain is not likely related. Consider ENT evaluation.
Thank you for your response. This is my first time to get a terrible sick and pain in neck. Which doctor should I go for ENT evaluation? Should I go back to my endocrinologist? Please reply me so I know what to do.. I appreciate your advice.