Years ago I had a similar experience. I was hunting with a buddy were spaced apart about 30 ft or so. It was after dark and we were leaning back against the trunks of a few large osage orange trees along a large tree fence line. A great location so we thought facing into some heavy cover.
I was calling fox at the time, long before we had coyotes and any kind of bobcat population. This was 40 plus years ago as I recall. It was a brisk cold, very still nite. You could hear movement and any approaching animals due to the very dry frosty leaves that were all around this area.
I made a few series of calls and not long after the second series of distress calls I thought I heard some slight noises behind me. I became very alert at that point then the noise stopped. A few moments later I could feel a slightly warm / panting breeze sensation on the back of my neck and lower part of my head. I then picked up a sort of foul odor drift to my nose.
After thinking for a brief moment what could that be, I realized what it most likely was. I jumped up and turned around to look behind the tree. Once I looked briefly around I caught the fleeting animal with my head lamp running away. No chance for a good shot. That old fox got that close without me even really knowing he was there until he was on top of me.
It certainly was a wakeup call for me and my partner. He heard and saw me jump up and make some comments. It was a memorable nite.