Type of specialist dr. who treats sacroiliac joint pain?
There are several different types of doctors that can help. Sports medicine doctors can help, and they may refer you to a physical therapist. You may be able to learn some exercises to help you feel better.
A neurologist or orthopedist, or both. And possibly a rheumatologist.
A physiotherapist can do that.
Probably an orthopedist and they can sub specialize in back disorders