Maybe call your regular doc and see if you can get a sterile tube to collect fluid in, and see if your doc is able to just order the beta transferrin test with the associated blood draw. It seems like a pretty basic lab, I only went to ENT because I have very complicated headaches and I was looking for more opinions and they happen to be familiar with csf leaks. There are also ways to try to trigger more fluid called valslva maneuvers, usually involving straining or bending forward, but I would only do with a doctor helping.