One of my juvenile pictus geckos has something wrong with him... I think. Or at least, Id assume.
Ive had him about a year now, and he was maybe 6 months - 1 year old when I got him (judging by size). Hes definitely a male, but I couldnt tell that at one point and had him housed with a female and an adult male.
They got along for a very long time (the males that is), until one day I didnt feed them on the normal schedule and found this lil fella with his tail missing 
I was rather distressed, and after that he got his own enclosure and extra feedings, etc. For maybe 4 months now, hes been in an enclosure with 4 females, one of which (the largest) I recently paired with a different animal.
I have no idea what this is, but when I checked him this morning I noticed it.
Would like to know:
A. what is it?
B. how/why did it most likely occur?
C. how can I help him, if he indeed needs help?
