What Is The Bruising And Pain In My Outer Thigh?

Hi, for the past week or so now i've had a pain in my right outer thigh that feels like there is a massive bruise there. but there is no discolouration or anything and i know i cant have pulled a muscle because i havent been doing a lot of exercise. But in the last couple of days i think be getting a little bit worse. it hurts even when im just sitting down. Please help! thank you!