Spot on my WTF's nose....

[Kmoonleaf]

I mentioned this in a different thread a few weeks ago, but got no reply, so I figured it would be best to make a new one just for this topic...

My precious Whites Tree Frog, Mordin, Has had a blueish/whitish spot on his nose ( just to the right of his left nostril ) for at least a month. It's really hard to get a picture of, but it's definitely there. It might've been around for longer, I've had him for 2 months and I don't really remember when I first noticed the spot. Here's a picture of how it looked a few weeks ago:


And now, it's turned darker, almost black.



Does anyone know what this could be?? He'll let me touch his nose, but if I try to touch that spot he backs away, leading me to suggest it hurts? Otherwise it doesn't seem to bother him, but the color chance is concerning me.

[Kmoonleaf]

for clarification: