Investigate your pump, look at the shaft where it goes into the wet end for any evidence of a pump seal leak. If it appears wet or you see chemical residual or corrosion, have it serviced or you will be buying a new pump. This is where it goes from a $70 to $100 repair to a $400 to 600 repair.
The other issue could be something has been sucked into the wet end and like a spinning tire could be oscilating or out of balance until you take that "something" out. One way to check, you will get wet so turn the power off, is to open the suction fitting on the side of the pump and stick your finger in there, you did turn it off first didn't you, to clear or free any twigs or debris to come out with the water that is purging out and then close it back up being sure the "O" ring remains in place.
OR, call a service person.