Trying to figure out the right kind of doctor to see for a condition. pain, numbness, tingling in my left arm for about a month now. neurologist or rheumatologist?

Orthopedist: Consult an orthopedist first to find out if there is impingement on the nerves. He/she will refer you to a neurologist if no orthopedic issues found.

Neurologist: Your question is one which is very reasonable. Localization needs to be done initially, which would be best served by a neurologic consultation. This might be supplemented by either/or imaging studies and electrodiagnostic testing.