WebMD and Black Elbows

You know you have a problem with self diagnosis when you're getting ready for bed and you notice the black elbows.  
My elbows are black.  
I wash them with soap and water.  
Still black.  
Make my bed, fold my laundry, go in to brush my teeth and stare at the black elbows.  
Yesterday's event pour through my head.  
Today's event go through my head.  
Nothing.  
No planking.  
No elbow use at all.  
As I'm finishing brushing my teeth, I know I need to look at WebMD to determine what causes black elbows.  
Hopefully it's just a side effect of something.  Not a precursor to my doom.  
Finish in the bathroom, begin the long trek to pick up my phone and determine what is wrong with me....  
Lucky for me the lightbulb went off.   I wore a black sweater today.  A new black sweater.  My elbows are died black.  
Lucky for you, I'm not dying from black elbows!!!  You have lots more time with me.