Hi , probally no one has respounded because its very difficult to be sure whats wrong with a animal through anothers eyes.
idea #1 I suppose its possible the animal was born deformed ? I certainly wouldnt breed her until I was sure she doesnt carry any disabilities.This is a stretch ...
idea #2 Cresteds have so very few health problems compared to many reptiles it seems likely that shes deformed and suffering from a calcium crash . I personally have never experenced a crash with any of my breeders but it seems I have read that the yawning is a symptom . (I wish I could say Im sure of that)I do know that spasms are if you see her experence that.
Typically the jaw is soft and possibly lower jaw too short .
You can get a idea of her calcium situation by looking into her mouth (usually gently tapping on her snout will cause her to open her mouth) on each side towards the back of the throat are calcium sacks on ahealthy gecko those will be easilly spotted.
I recommend feeding her Crested Gecko diet .Its a complete meal that requires no supplimentation and as mentioned before Ive never had a calcium crash from a single animal.
Lastly... the best advice is too take her to a reptile vet ...unfortunatly they are few and far between and will cost you as much as the value of the animal itself.(Not that the animals life isnt worth it ,but if its not a reptile vet it could be wasted money as well)

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