How much does she weigh? My undersized hatchlings usually have very narrow heads, but as has been mentioned, they do just fine. She does have a very fat body for that head, though.

You said she shows signs of 'mental retardation'....just what exactly does that mean? (How would you judge an intelligence deficit in a ball python?)

If you meant that she has neurological symptoms/discoordination, that's entirely different. Does she have a visible jaw deformity? Have you looked in her mouth? (Use a soft rubber cake spatula to open it).

Jaw deformity X neuro symptoms to me says 'incubator temperature swing'. Dips or highs past a certain point can and will cause deformities and losses very quickly.