it's not broken but you might have torn your ligament...if you keep it untreated it might get stiff and you won't be able to use it as well as you used to. The best thing would be to make an xray but you could wait for a couple of days to a week, to see if the swelling is going away. If not, go see a doctor! Anyhow, if it's not broken you won't be able to use the finger for at least 4 weeks.