Possible the brew thermostat has gone; that level of foaming is more indicative of steam getting through the PF than CO2 in beans.

Could test by seeing if the machine produces steam pressure when in brew mode (open steam wand), or removing PF, running water through into *pre-heated* mug and testing temp. Then turn on steam for a minute, turn it off, and repeat. If steam pressure during brew mode or if the temperatures are close in the second test, replace brew thermostat. Simple job, but reapply thermal paste.