Re: wet spot on ceiling under inaccessible attic
Yup, very rarely are leaks actually located where drips or moisture damage occur. Look higher up the roof line. I fully understand the inaccessible attic situation. Still, get where you can access and inspect the underside of the roof from ridge to soffit. Look for any discoloration or water staining, even if it's just a hint, then inspect the surface wherever you find telltale signs from underneath.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!