2009 Jeep Liberty Coolant

I have a 2009 Jeep Liberty. I currently went on a trip to Chicago (about a 5 hour drive). I stopped at a store in Chicago and when I went to turn my car back on it wouldn't start. I noticed that the temperature gauge was hot. I checked the antifreeze and it was low so I went back into the store purchased antifreeze and filled it up. However, there was absolutely no leak on the ground and I could not smell the antifreeze leaking. I drove around Chicago and back home. I checked the antifreeze when I got home and it was low again. So again I filled it back up (no leaks no smells). On my way into work this morning my car ran completely fine didn't over heat and the temperature gauge stayed in the middle. However, I noticed a bit of smoke coming from my defrosters (that or it was really dusty and somehow air was coming up and blowing it around. What could this be? I am due for an oil change and the last time I got an oil change he mentioned that I should probably do a radiator flush or a coolant flush (I cant remember the exact terms) would this fix the problem?