She looks older than 3 months if you bought her beginning of july. 12x12x18 is pretty small especially for basking at 90 degrees. Either way its way to small for a juvenile veiled I think. Have you cooled her down at all. I wouldnt be surpised if she was overheating.
Could she have possibly choked? I've had one of my panthers get a dubia lodged in his throat luckily I was there and able to pull it out with feeder tongs.
If she's laying on the floor of the cage with her tongue out like that she's dying. Sorry to have to tell you that. Spraying her tongue could be drowning her when she's laying like that if she's still alive.
