I know this is a little late, but I would suggest seeing a DR for an xray of that finger. Any brand new symptom should be reported, and I would worry about a blockage of some type of draining. (I still don't know enough about RA to know what is happening)
Hairline fractures can occur in your sleep, as well as stress fractures if you bent it long enough (under your pillow). if you take sleeping meds, and still woke up to notice pain in your finger, that was probably significant pain- even though you didn't notice it much.
I would suggest it is at least worth a phone call so that the DR can decide if she wants to see it or not. They would want a description of size and color. Good luck, and I hope this message is a day too late and the swelling is already gone.
When you cannot stand, on whom do you lean?