If it were me I would cease adding the liquid calcium and continue dosing the reef builder ( half dose what you normally dose ) and continue monitoring the levels.
The calcium should drop, and the alk should rise.
Once you get the dKH up around 10, and the calcium back down into the 380-400 range - stop the reef builder and wait awhile to see how the tankwater responds before dosing anything again.
What do you have in your tank in way of corals & coralline algae and live rock ?
What is your normal pH range ? high / low ?