If you were south of Mud Gap down by a creek that probably means you were hiking up the Sycamore Creek trail next to . . . uh . . . Sycamore Creek. There are three prominent switchbacks on this trail (a 7 mile climb from Tellico River/Fish Hatchery to Whiggs Meadow with a gain of 3,000 feet).
I'm thinking you probably missed the third switchback and went up parallel to the creek on a faint trail which ends in a small campsite right above the loud creek. I call it Hobo Camp and it's one of my fave CSs.
Attachment 45744
Here's what the side trail away from the BMT looks like---with Sycamore Creek down to the right.
Attachment 45745
There used to be a BMT trailsign on this post at the mentioned switchback---gone now. People don't see the switchback to the left and continue straight up into that campsite next to Sycamore Creek.