It can be very worrisome when you are in limbo waiting for a "real" diagnosis. I am sorry hear it had been so stressful on you. Rest assured the tests you are having preformed are exactly what you need in order for your doctor to learn more and make a diagnosis. Your eGFR and Creatinine levels being normal is positive news. Do your best to eat healthy, take a walk, or read a book to keep your mind busy. If you care to share, what make you go in for testing to being with?