I have problem swallowing and eating food, should I be concerned its thyroid? What should I do or what causing this?

See doc for an eval. Your problem is obviously affecting you in a signigicant way and so it is time to get it checked out. Thyroiditis (inflammation of thyroid) can cause such pain but this you can feel by palpating the thyroid itself. Aphthous in back of throat can cause severe pain. There are other causes, but it is difficult to tell w/o an exmination. So, i suggest consulting your doc. Good luck.
Esophagus. It is much more likely to be an obstruction of the esophagus or back of the throat. Be seen by your regular doctor or gastroenterologist.