Right Wrist and Arm Pain

Two years ago I had a heart catheterization performed and my doctor elected to do it through my right wrist. Over time I have had off-and-on soreness and weakness with my wrist but nothing to cause any alarm.

Approximately a month ago I began having more problems with that wrist consisting of more prolonged weakness and longer periods of moderate to severe pain. However, each time it may last at most a day and then go away.

Now, for the past 3 days my wrist has been in severe pain causing me to barely use it and over the past 36 hours or so, I have developed a knot that has come from not being visible to at least the size of a quarter. This knot has came out of nowhere and is causing severe pain and limited use of my entire right hand and arm. Also, I am now experiencing some numbness and tingling up my right arm to my elbow and slightly beyond.

What might this be? The knot is located almost directly below the remaining scar where the heart catheterization occured over 2 years ago. Why has it grown to it's current size in less than two days? Scar tissue? Cyst? I realize the numbness and tingling is most likely from the knot pressing against nerves. The pain is unbearable and now that it is worsening I figured I may need medical advice. Any suggestions would be greatly appreciated as I am contemplating seeing a doctor or not.