4 past month feet turning bluish purple when sitting or legs crossed. The left foot not bad. Right real purple. What dr to see? What's going on?

Congestion. Purple is when blood pools in your foot. When sitting the blood hangs down or when you cross your legs you stop the blood flow. Its a vascular issue so you could see a vascular surgeon, there could be a problem in your foot causing the blood pooling so you could see a podiatrist.