I checked the air pressure on the top of my tank and water squirted out. When there is a high demand for water the pump (submersible) clicks on and off rapidly then stops (with no pressure at the tank) for 20 sec or so before coming back on.
When the pump stops the contact-ors in the switch are touching. It will do this until the demand is gone. I can turn a tap on or have a shower OK , but when the tap/shower is on and someone flushes a toilet it happens. Any help would be appreciated

"i checked the air pressure on the top of my tank and water squirted out."

Typical sign of a ruptured bladder in your pressure tank. It needs to be replaced. As a short term "get by", you can turn off the breaker, drain the tank with an outdoor faucet until pressure is zero and the tank is empty, use an air tank to put 10# or so of pressure in the tank, then turn the breaker back on. Your system will work better, but the problems will return. Replacing the tank is the only permanent solution.

Thanks. Do you know what causes the bladder to fail?

Usually, it is simply age. There are some tanks that the bleach used to "shock" a well can damage.

Thankfully, tanks are not terribly expensive and replacement is fairly simple.