Sarina is 52 years old and presents to the GP with a 3 week history of pain underneath her right jaw line. She has noticed this comes on soon after meals and that the area sometimes briefly feels swollen also after eating. There is no history of dysphagia or weight loss. She was seen recently with a sore throat which has now settled. She is an ex-smoker.
On examination, observations are stable and you note a tender swelling in the right submandibular area.
What is the most likely diagnosis?