Hi, Friday I Went For A Morning Jog At Santa

hi, friday I went for a morning jog at Santa Monica college. two hours later after I got home I felt a pinch on the right side of my knee beneath my jogging pants I immediately squished the insect. It's been two days and its gotten bigger and wider. it doesn't itch but it burns and bothers me a lot to walk and bend. Should I be concern? should I go to the ER? I am worried because I've experienced many mosquito bites, spider bites and once bug bites but nothing burned like this.