OIl spraying out the dipstick

Hi all

for the last fortnight oil has been spraying out the dipstick.Changed the seals and that did nothing.
Had it to a mechanic and he's saying there is a massive pressure buildup in the sump and the headgasket might be gone.
This sound likely?Has no milky deposit on the oil cap.I do have white smoke from the exhaust and bit down in power on hills but thought that'd be oil sucked in throught the air intake.
Any ideas please let me know.I forked out 1500 on a new turbo already this year and can do without the gasket too

Thanks all

blocked crankcase breather, after that new pistons and rings

You may want to check the engine breather filter 1st.