Diagnostic protocol for trauma-induced CSF leak?

What is best, conservative protocol for diagnosis of CSF rhinorrhea? Facts of case, hit head with a hard blow to the side of the bony bridge of the nose resulting in significant bruising and swelling of nose, however ER xray showed no nasal bone break. Nasal xray was only xray taken. At time of blow, heard distinct "crack" sound in head, (thought perhaps nose was broken.) Also, immediate, profuse, clear salty, tear-like liquid running unilaterally from nose and down back of throat on the same side as the blow. Dizziness, confusion, slurred speech and terrible frontal headache after trauma. Did not know about CSF fluid, was only asked if I was bleeding at ER. Went home. I am overseas with limited medical choices. Apparent unilateral CSF leak for 3 months now. I hear a noise, like a crack, when I turn my head sometimes and the flow the increases. Have collected fluid. How "fresh" does specimen need to be? Refrigerated? What are logical steps for diagnosis? Lab test of fluid, then MRI? would greatly like to avoid CT scan due to radiation risk, if possible. Flow of salty fluid has lessened compared to the first few weeks, but still detectable. Any opinions?