Paint parasite?

[Clutch]

Hello everyone –

I’m seeking wisdom on this puzzling problem with my paint that developed very rapidly. I’ve never seen anything like it. Hope the pic is clear. This blotching area sprang up in a matter of days on my right front fender – but only the fender not the hood. This leads me to rule out an external spillage since it would have gotten on both. Likewise I see nothing happening under the hood or in the wheel well that could seep out and damage the fender. The surface remains smooth to the touch.

It appears that something is coming up through the paint – or is it down through the clearcoat - or is *between* the paint layer and the clearcoat layer? Is that even possible? It looks like it’s eating the paint, thus the term “parasite” for lack of a better description. Could this be rust coming up from underneath? Anyone ever seen anything like this? Any ideas on cause or cure? Can it be fixed without a total strip and repaint? I’m stumped, so thanks in advance for any comments or advice.