First of all, how incredibly unprofessional to make you uncomfortable when all you want to do is get the right kind of care! This, unfortunately, does not sound unfamiliar to me. I experienced a similar 'hissy-fit' by a very well respected rheumatologist at the Univ. of Minn. who was offended that I had sought additional guidance from a team of doctors at the Mayo Clinic (my primary rheumatologist referred me to both of these places.)
This nephrologist clearly had a problem with the course of treatment your rheumatologist determined. If so, then THAT'S where he should've directed his frustration - not at you, for goodness sake.
I think, for most of us, our rheumatologist is the one to act as coordinator of our health care - someone has to keep all the balls in the air, and the patient is generally not qualified to make a diagnosis or treatment decisions!
I'm so sorry you have to worry about something like that - you have enough to worry about without dealing with a 'pouty' doctor. Grrrrrr
So, will you ask your rheumatologist for a referral to another nephrologist? I certainly would - and I would be very frank about your experience.
"If you trust Google more than you trust your doctor than maybe it's time to switch doctors."