We have a well for our water and lately when you turn on more than one faucet the pressure dies down to almost no flow. I also notice the expansion tank, i think thats what it is, has a pressure gage that turns on the well pump when the pressure gets to a low level. My problem is that the pressure vale is clicking on and off like a blinking light, it goes from 50 psi to 72 psi and back and forth within seconds of each other constantly until the faucets are shut. I'm sure this is not right. Any help would be appreciated.

Joe