bearded dragon tail problems

Question
hi, i have a beardie that seems to be having problems with her tail. It has turned black on the end and right above the black part it looks like there are scales missing. She seems to not feel her tail if i touch the black part but will respond if i touch above it. I was wondering if it was dead or if you had any ideas about what it could be or what to do about it. I don't think it is the housing because I have 3 other beardies with the same setups and they are doing fine.

Answer
Hello Laci,
So you are housing the dragons all separately, correct?
Can you post a picture of the tail for me so I can see it.  Thanks.
Did she possibly have some retained shed at the end of her tail that has caused the necrosis?
Is it shriveled up?  
Could she have caught it on something to injure her tail?

Tracie