Blue/black stain on my ankle. I am desperate. Please help!

Hello all. I don't know anymore what to do and what kind of doctor to search. I really hope someone would come up with ideas. In the beginning of the year (8 months ago) i woke up one day with a burning pain in my left ankle (from inside exactly where the bone is). It was kind of red but nothing scary. It began to worsen.it is important to say that i had no trauma. After 1 week it had this strange red/blue/violet color. It hurt and it was swelled. It was like i had another bone right next to my ankle bone. Then my journey began. Ive seen all different kind of doctors. Skin doctors, trauma doctors, orthoped. I had rentgen picture and MRI. It didn't show nothing bad. Then one doctor Dermatolog decided that it can be stain from Lyme disease. I haven't seen any insects but i've started to take antibiotics for months. Unfortunately It didn't get any better. Now it is one little blue/black stain and sometimes it hurts with a pulsating pain. It is not bump anymore but it is still there and i know that this is not normal but i am out of ideas. I would appreciate if someone have any ideas or share similar experience. I don't know what to think anymore. Thank you!

Could this be a vascular problem? Something to do with a weakness in your veins? A vascular surgeon may be the person you should see.