The Happening Red Band Trailer I Pop My Wrist With A Rubber Band And These Red/purple Dots Show Up All The Time, What Is This?

I pop my wrist with a rubber band and these red/purple dots show up all the time, what is this? - the happening red band trailer

More harm than me emphasize I am not easy to relieve by blowing up the wrist with a rubber band. But shortly after they appear small dots on the wrists and not disappear for a while. It was probably more pressure is applied when the elastic is obvious, but what? and why is this happening?