Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry for this concern for Charlie.
In most cases, the presence of a small amount of blood in the stool or present by itself is not a great cause for alarm. It usually means that there's irritation to the colon and nothing more than that.
I'd actually expect Charlie to produce some blood as the bone is making its way through his intestines.
Dogs can usually digest about any bone they might eat given enough time. The biggest concern is whether the bone will soften before it causes trouble such as an obstruction. However, most dogs will pass these bones with no significant issues whatsoever.
But if bones were ingested and the patient start vomiting and/or become lethargic and/or stops eating, then I worry that these dogs might be obstructed. The fact that Charlie is otherwise acting fine is excellent news and means that he's less likely to be obstructed.
What you can do to help move things along would be to increase the fiber in his diet by adding canned pumpkin (NOT the pie mix). You can give him 1 tsp twice a day.
You could also give him raw bran flakes such as wheat bran at a dose of 1/2 tsp daily.
If his stools are already loose, though, the above may worsen the situation. If that's the case, then I'd feed him a bland diet of boiled chicken and rice which may help settle things down.
At this point, unless he's producing a profuse amount of blood, this wouldn't be considered a critical situation. You can continue to monitor him for evidence of the bone in his stools or for the signs I mentioned above which might be suggestive of an obstruction.
I hope this helps to provide at least a measure of reassurance about him. Deb