I had seen a specialist orthopaedic surgeon and they discovered a "tumor" in my left lower leg (tibia). what kind doctor should i see? what could it be? other than that, my whole body is inflamed - which is being treated.

Orthopedic surgeon: Orthopedic surgeon would be right specialist for the lesion you mentioned. You may need to consult an internal medicine specialist if you have other symptoms. Wish you good health!

Tumor bad or good ?: Tumor just means an abnormal growth, but this could vary in importance from a innocent bone cyst to cancer. The orthopedic surgeon you saw should arrange any further evaluation if it is needed. It sounds like more communication with those already involved is where you should start.

Orthopedic oncology: In many cases like this a multidisciplinary approach(think physician of different training working together) works best including an orthopedic oncologist, surgical oncologist, medical oncologist and radiation oncologist.