Solar panel output voltage drops
You might have a panel which has a basic characteristic like this (admittedly this is a much higher power panel but the principle is the same): -



If you go along the baseline, the panel has an open circuit voltage of about 20 volts. If you short it out it will (maybe) produce 5A or whatever your panel is rated at BUT, this is for a certain level of sunlight. If you look at VI curves under different conditions you get something like this: -



As you can probably see, in worstening sunlight conditions, the ability to deliver current is dramatically reduced (even though the open-circuit terminal voltage is roughly constant at about 20 volts).

So, make sure your meter is working correctly and look up the data sheet for the panel and calculate an appropriate load resistor and repeat the test. If you are measuring an open circuit voltage then it's highly likely that the panel is OK.