Black dots under armpit?

So today when i was doing our daily grooming routine i discovered a few black spots under one of his armpits.


it looks like a bunch of black head spots next to each other and its only under one armpit!
We give him baths so i dont think its that hes dirty, Help?   :-$ 

Im scared it might be early signs of lichenification?!?!  

is it because of the shampoo? SHould i try another one?

Hard to tell from pic, could they be little skin tags?

I can't really see anything in the photo, does he wear a harness? Or it literally could be a rubbing, its hot for them atm x

does it bother him at all,ie does he itch it,may be pop him to your vets if it does'nt go.

Well he doesnt seem bothered but ill take him to the vet anyway as he hasnt had any checkups done since i got him and i need to learn how to trim his nails if need be.

Always good to get an MOT never had Moo's nails clipped though Xx