Something is blocking (or overwhelming) the crankcase ventilation system
and pressure is building up inside the engine. That makes everything
If it were my car, I'd start at the air cleaner and work backwards to,
and including the valve cover. Check that the passages are open, screens
clear etc. and clean them if there's any doubt.
Inside the valve cover is an oil baffle; it may be clogged up. If so,
there's a reason for that, either the engine is running too cold, or
being driven only very short distances so it can't warm up or the oil
changes are too infrequent or the oil is poor quality.
If nothing is found you must consider a blown head gasket; its symptoms
are oil in the coolant, coolant in the oil, overheating, irregular idle.
A compression test ought to be done to confirm low compression before
removing the head.
The 110 is a solid engine and a sudden event like this has a specific
cause, you need to find it.