poor baby girl :( I hope you figure out what is going on with her and it is fixable. Will keep your baby and you in my thoughts. I so hope it isn't permanent.
Did Mom have any problems foaling? Was she carried over long? Did labor last a long time? Any signs the umbilical cord wrapped the foals neck? Red bag birth? Any excessive bleeding from the umbilical cord? Any way she could have been exposed to tetanus, as in not doctoring the cord stump?
"Light travels faster than sound. That's why some people appear bright until you hear them speak."
Larry the Cable Guy