Big White smoke clouds out of exaust

I was driving normally when i noticed a huge cloud
of smoke in my review mirror. I decided to drive
away from the cloud but realized it was coming
from my car. No check engine light. No overheating.
Engine was running fine. No abnormalities besides
the smoke. I pulled over right away and checked
the exhaust and noticed what seemed to be a
mixture of water and oil. I checked my oil dipstick
and no oil was present. I had just done the oil
change about two months ago so that was odd. I
want to know what it might be before taking it to a
mechanic so i have an idea of what to expect and
not be ripped off. Thanks!!!