paint problem

[STUKA]

I have a 86 300E that is metalic thistle green, a very unique and beautiful colour.
While washing it yesterday in the fading daylight. I noticed a cloudy patch about the size of a quarter dollar piece on the roof between the gutter rails. I have never noticed this before and it is not readily visible. The surface over the area is smooth and the patch seems to be in the clearcoat or under the clearcoat. I searched "detailing" and could not find anything quite like this. The paint is in great shape and many people think that it is a new car.

Questions:

1.) I have tried 2 cycles of #9 on the roof
section(entire area between gutter rails)
and noticed no change. Can I just work
the patch area with additinal cycles of
#9?, Or should I repeatedly do the whole
roof section?

2.) How hard can/should I work the #9?

3.) What am I dealing with here?

Thank you all for this wonderful site.

P.S. This colour would look great on a 500E.