I have sudden stinging purple blood clot in r ring finger knuckle.over the past few hours, this sting has gone to r hand, r arm. is this serious?

Hard to know: Without seeing and examining you there is no way to know what is going on. The ascending nature of these symptoms, however, makes it imperative that you seek medical help asap. You need to make sure this is not infection spreading rapidly or some other serious problem. Please go and see a doctor now.

Likely: Concern for embolism or thrombosis.Seek attention now. Vascular surgeon likely best option.