From your description, it does sound like your dog has a small foreign body under the skin. A piece of a stick is the most likely, particularly if he runs around in a woody or shrubby area.
The biggest concern is infection under the skin, so I think it would be worthwhile for you to try and remove it. I would approach it sort of like you would if you had a sliver. Put warm compresses on the area (a wash cloth soaked in hot water and then wrung out works well), pull off the scab, and see if you can work the sliver back toward the hole. If so, hopefully you'll be able to grab it with a tweezers and pull it out.
If you get it out, then clean the area with 3% hydrogen peroxide for a couple days and monitor it for any pus, redness, or inflammation.
If you can't get it out or it is just too painful for your dog OR you do get it out but there is an infection there, you'll need to take Moses to your regular vet. They may need to sedate him and remove it that way and they will likely put him on antibiotics.