The only check valve that counts is the one on the submersible pump. Do you know what type of pipe you have between the house and the pump? Based on your description of what is happening, you probably have a leak in the drop pipe going down the well or the check valve on the pump is bad. It is also possible that the lateral pipe between the well and the home is leaking. This is even more likely if the ground has been frozen as a frost heave could damage the pipe.
If you open the well cap, you might be able to hear it if the drop pipe is leaking. If it's the lateral and the well can produce enough water, sooner or later the water will start bubbling up out of the ground. In any case, these types of repairs are best left to a pro or someone that has the resources of one.