A 28-year-old man from rural Maharashtra presents with a 5-day history of severe left-sided neck pain, dysphagia, and fever (38.5°C). On examination, he has trismus, left intraoral swelling pushing the soft palate medially, and a palpable firm mass in the left lateral pharyngeal wall. Neck movements are restricted. Laboratory studies show WBC 14,200/μL with left shift. CT neck with contrast reveals a 4 cm hypodense collection in the left lateral pharyngeal space with rim enhancement. What is the most likely diagnosis?