That is terrible -- I am so sorry for you and Oz --- it is heartbreaking to find them when you were trying so hard to figure out the cause and correcting it ---- I am thinking something else was going on here something that maybe it was genetic - you wouldnt know and to find out you would need to have a necropsy done- he was so little and thats what makes it worse I think ---
again I dont think it was you I think there were other things going on here -- since we are not exactly sure of what happened I would recommend disinfecting your tank w/ some F10 or Rescue or some Zoo Meds WipeOut-- disinfect everything in the tank --- in time you may want to try again and w/ all the help you were given you know how to get your basking temps and your UVB correct --- that is the lifeline of the dragon -- so even w/ you getting this corrected little Oz had other issues at hand normally a healthy dragon would of been fine and bounced back as quickly as you sought help -- its when people let them go to long w/ out getting help that is a issue and sometimes they cant bounce back --- again I am sorry to hear about him