I'd say you definitely overcarbed it. From your description, it sounds like you left it at 25 psi when you shook up the keg. If so, that was where you went wrong. For burst carbing, you should have lowered the regulator to serving pressure first (usually 10-12 psi, or thereabouts), then shake, roll, etc.
To correct, turn off the gas and vent repeatedly over several days until the carb level gets to where you want it, then put it back on the gas at serving/set-and-forget pressure and leave it there.