I Have the grand kids tomorrow. I'll get a splint for it. Thanks for the tip, Brian!
Very welcome, kids can be stubborn. As Dave said above, try to impress upon him the painful future consequences of improper medical care. Otherwise, see if there is any discoloration or discomfort when you gently move the finger around. Those things can be a sign of something much worse. If none of that is there, a jam may be all it is. As I said, I'm not a medical person. My advice is from my own experience and a mother who was a nurse for many years.
He will want to keep the splint on for the first 48 hours, then he can remove it to shower but needs to go back on after he dries off. The worst time of potential damage will be when sleeping. Keep it on for two or three weeks and all should be good.