What Causes A Painful Bruise On My Leg Without Injury?

I've been having leg pain for the last month. It started out as a burning and stinging pain in my inner left thigh and now it's a achy pain. I've also been have muscle twitching in my legs. Now I have a spot on my leg that when I rub it it feels sore, but I haven't injured it or anything. What could be going on? Should I worry about blood clots?