cold rubric

[Shannon Nelson]

What rubric (or anything else) applies:
Son was out in the cold, when came in, fingers hurt (not unusual).
After a while, when he warmed up, they went back to normal--except one,
which is now swollen. He says it feels normal except for the swelling.
I assume this will go away on its own (how long), but am curious
whether it has associated remedies, or anything else about it?
Thanks!
Shannon