Keg Leak, help!

Guys, I have had a keg leak for some time now and am getting rather frustrated. I have replaced just about all of the moving parts on the keg, have sprayed all of the connection areas with Star San and have not been able to discover where the leak is coming from.

A little about my setup, I have a refrigerator in the garage that has both my keg and my CO2 tank inside it. I do not have a temperature controller on the refrigerator (bad on me, I know). I set my regulator to 10 psi and it stayed there for about a week and the CO2 level in my tank remained unchanged. Then it started getting hot outside, in the 90s, and the pressure in my keg shot up to 20 and the CO2 level dropped by nearly half. The temperature has fluctuated here in Alabama from the mid 60s to low 90s from day to night. Could this temperature fluctuation be driving my leak or is it most likely something in my kegging system?

What exactly is leaking? Is it emtpying your bottle of Co2 or is the guage just going down? Do you know if you are getting large temperature swings inside the fridge?

It is my CO2 tank that is going down, I have had about 5 or so completely drain on me with two different kegs and about 4 batches of beer. I'm assuming the temperature has changed anywhere from 20-30 degrees on a daily basis inside the garage so I'd assume the fridge may be taking some temp hits too.