You shouldn't see thinning of the skin from just one day of using it. You may be seeing symptoms of whatever it was that caused you to use it in the first place.
Have you seen a doctor? You should. Not knowing what caused you to use it in the first place, and not knowing how much is the cream (though it seems not likely that it would be the cream) and how much is whatever was going on first, it's hard for anyone to say why you see thinning.
Let your doctor check it out.
The cream is a steroid. It is not appropriate to put steriods on some areas of the body. It should only be used as directed by a doctor.. Make sure it is completely washed off of the area. I would think that after a while it should return to normal because you only used it for a total of 8 hours. :)