Let me try if I learned anything from the pro's here on the forum.
Cut the power off and drain the water from the pressure tank.
Then put 28 PSI of air in the tank(2 PSI below cut in pressure of 30).
turn the power back on and see what happens...if it has a 30/50 pressure switch it should stop at 50.
If not maybe the line from the pressure switch is clogged or the pressure switch is bad.You can buy a 30/50 square D pressure switch pretty cheap at the HD.
Worse case scenario is that you might have a busted line somewhere between the pump and the house.
But let some of the pro's react on this one...I might be going in the right direction though