New dark spots in fur

Hi! Our JRT x has recently (very recently, just in the past week) developed LOTS of dark spots in his white fur. We can’t see any change to the skin below. We also don’t know exactly what age he is..rescue dog with very little history but POSSIBLY around 10 now. We can see him looking older, his hearing and eyesight aren’t what they used to be, and he has a constant shake (Like Parkinson’s in a human). He’s also recently started retching in his sleep although he’s never actually sick. any ideas?

Hello!   Are these tiny black spots, e.g. flea dirt?   (your search-engine image option will bring up plenty of example pictures of flea dirt to compare it to, I'm sure - they come loose and make a smear when smudged against damp cotton wool).   Or by 'dark spots' should I picture clogged pores, or perhaps areas of discoloured hair?  The latter mostly manifests when hair is saliva-stained and turns brown, often over an area that is continually exposed to saliva e.g. a painful, arthritic joint that is licked, an area that gets drooled on a lot or the itchy skin between toes.  Brown fur can also represent bacterial or yeast skin infections, or occasionally underlying hormonal changes.  Whichever way, it sounds as though a visit to your vet might prove useful.   We hope that they get to the bottom of it for you!