What Could Cause Discoloration On Legs Due To Slightly Reddish Blotches?

just wondering. I have been seeing a dermatologist. the dermatologist was unable to diagonse what these blotches that are discolored on my legs. He had given me a prescription. Its been this way for months. They have faded some. But at one point they were darkish red and now some what slight redish but blended with my skintone too and not as raised as before. I just thought I would ask another opinion. On left leg they are located on the front just below the knee and one just above the front near my ankle and one on the back of my calf. One right it is on the back part just above my ankle and on the front part just above ankle. Any Ideas