What Causes Bruise On The Inner Thighs?

i have a bruise on my inner thigh for 2 weeks now. It is slowly fading.What I find strange is that it looks like a perfect ring, white in the middle and if I push on it it is swollen underneath but not on the surface. Around the ring are small cirlces of blood that looks like it pooled and mimics the same picture around the ringed bruise. The leg area was tender for a week when I walked or touched it. Not so much now, but still sore. Should I get this looked at? I am a 40 year old female and in good shape.