Rapid oil loss with no signs of leaking is never a good sign. Step one would be to pull the codes and see what they are.
If you do not have access to a code reader (most auto parts stores will pull the codes for free) then there is a trick to doing it yourself.
To pull the code, do the following without
starting the engine: turn the key to the run position, off, run, off, run.
Do it fairly quick. When you are done, the codes will show in the Odometer
as the letter P followed by 4 digits. Write them all down. When its done,
it will read 'Done'.
When you have the codes you can check them here:
My guess is you will find engine misfires, at which point I'd probably say it's time to pull the cover and have the engine checked. I'm guessing a blown head gasket (you should also see a milky color to your oil indicating the presence of coolant) or a serious cylinder/head problem.
I had the same symptoms with an almost brand new Ford truck with 14,000 miles on it while trailering my boat home from a bass tournament about a dozen years ago, sudden oil loss with no leak, engine chatter and check engine light. It turned out to be a cracked/dropped piston.
Welcome to the forum by the way, I wish your visit was under better circumstances...