2 switching power supplies.....and diodes
Schottky diodes are quite leaky (worse when they are hot), and you have no resistor to ground. It's reading the leakage current through the diode and the input resistance your meter (probably 10M or something like that). Low breakdown voltage Schottkys tend to be worse. 

Consider the common garden-variety 1N5819:



Edit: As you can see from the above specs there is no guarantee that 10K will be low enough, but I've found 'typical' curves .. which you can use if you feel lucky. 



3V reverse voltage at 25°C represents about 1uA typically, so only 10mV across the resistor- probably no big deal. At 75°C it's more like 0.03mA so you;ll have about 0.3V across the resistor 'typically', getting significant.