Automatic Transmission Problems?

Last night, I was driving - the car shows no sign of slipping at all, transmission is running FINE. I come to a stop sign, and go to turn and the gas goes fine, and within two seconds - i'm just revving my engine while i'm still in drive. So I pulled over and turned off the car after putting it in park, tried it again, and tried each gear(Reverse, Overdrive, Drive, 1st) and it just revs. Everything else works fine, and a friend came over and checked my and the gears lock in perfectly, the transmission fluid is fine - but there was a weird smell. Could a clog filter be the problem or what? It's my main car and I need answers fast. Thank you!