water pressure drops

I have a 5 year old well with a goulds sub. pump and a pressure tank that is buried in the ground. The well is 165 feet deep. My water pressure gradually drops to almost nothing at each faucet in the house until the pump comes on and then pressure is fine and the cycle repeats (the pump kicks on about every 10 to 12 minutes with water running). There are no leaks in the house plumbing. I cannot see what the pressure is at the tank, as it is buried. This has just recently started.
Any ideas before I start digging would be appreciated

If you meant 12 seconds instead of minutes, I would say start digging.

bob...

Bob, I did mean minutes, but the water coming out of the faucet just before the pump comes on, has very low pressure. Much lower than it had previously.

What kind of filters do you have? Not one of those so called "Whole House Filters" from a Big Box store I hope.

bob...

There is no filter. There is a water softner, but I bypassed it with same results.

pressure switch gone bad???
What is it set at and how old is it?

Check the pressure in the bladder tank...to do this, shut the pump off, open a faucet, wait until the water stops running, the using a tire pressure gauge, check the tank. My bet is that the pressure isn't where it is supposed to be - 2# less than the turn-on pressure.

If all the above checks out, see if the pressure switch points close when they should. You could have a clogged pipe feeding the switch, which would slow down it's coming on when it should.

bob...