The clinginess and the thirst make me think of aconite, but, you're the one with the half-decent homeopath, right? I'd just call her and get her opinion and then go out and buy a 30C kit.

Pulsatilla is thirstless, so I ruled that out, and, hopefully the cham. worked for you, but cham. children are usually irritable, angry, crying, and can only be quieted by being carried.

Good luck,
Snoopy