Probably just a coincidence that this happened right after you vacuumed. At the panel, that is at the equipment there are two screws top left and right. Unscrewing those will allow you to open and expose the board. Relay sockets will be on the top of the board labeled FLTR PUMP, Aux 1, aux2, and so on. Start with the filter pump (pump that is running?) and unplug the relay from its socket and then try to reset the small breaker. If it holds, then the problem is either with the relay, or the socket (circuit board). My guess would be the relay.
Note: You may try tapping the associated relay before you start this procedure. If tapping the relay shuts the pump off and you are able to set the breaker, change out the relay.