I have read all the post & answers on here .
But I have a similar question ,
OK my well pump keeps short cyceling & runs continually when the water is on
I checked the air pressure yesterday & it was rite 48 lbs pump comes on at 50 off at 60 I bought this house last yr have not had a prob till now .
I checked it again today & there is 0 pressure the water is running fine for now but my pump short cycles when I flush the toilet every 2 sec it does this about 12 times in a minute , when I run the water it runs until I shut the water off , I have watched the gauge when the water is on it doesn't drop below 45 lbs as soon as I shut the water off it turns off & the pressure is rite at 58 to 60 lbs could this be a faulty pressure switch or a bad tank ?
I hope this makes scence

Sounds like a bad tank. You spoke of checking the pressure on the tank, so this must be a bladder tank. Probably the bladder is ruptured, so you have a tank either full, or nearly full, of water. You can check this is in two ways. Depress the air valve for a couple of seconds. If water comes out, then it's curtains. You can also take a large screwdriver and start tapping at the bottom. As you work your way up, you will be able to notice a change of tone when you go from water to air. In your case, you will probably notice the change towards the top.

You can do a "get by" on this. Turn off the system and drain the tank through an outside faucet. Add some air to the tank through the valve on top to 5 or 10#, then turn on the system. This will work for several weeks until the air dissolves into the water. The only permanent fix is a new tank. Thankfully, that is a fairly simple install.

It sounds to be correct