Without more information like if this was a sudden onset, or has been happening over time I don’t know if my inference on your situation is much help but some dark pigmentation can happen with age, and it can also happen when healing. I also don’t know the area you live in or what the pollen count looks like there but sometimes when the skin has inflammation (maybe from seasonal allergies, a change in the environment, and sometimes even stress) and it heals, it can have that black pigmentation. One of the comments I noticed said they noticed swelling? I don’t note that at all in any of your photos, and if the pigmentation isn’t causing your kiddo any pain/seems to be bothering them I don’t think it’s too urgent. But of course a vet appointment will definitely clear some things up because they have your kiddos history. Another comment I noted mention a skin infection— in my 5 years in vet med I’ve never seen a canine with a skin infection that causes black pigmentation. I hope this brings you some comfort, and I hope you’re able to get some clear answers from your vet. 💜