Why really doesn't matter - it would B nice
to know, but it's immaterial.
Re-training is the same, whatever the cause.
I'd just start working on DS/ CC, DeSensitize & Counter-Condition, to convince her that U're the best thing ever.
That may mean putting a drag on her
so she can't flee effectively - an 8-to-10-ft-long light cord with no knots or handle, attached to a FRONT-clip on a well-fitting snug body harness, so that she won't be pulled by the neck, but brought to U hand over hand, if need be, or at least halted by the drag.
No matter how she gets to U, reward heavily - a jackpot to begin with is a good 1st impression. https://clickertraining.com/node/825
Jackpots need to be contingent
[connected discernibly to the desired behavior, in the learner's mind] & rare
A series of her favorite tidbits in half-pea sized pieces, AS FAST AS SHE SWALLOWS ONE, the next is under her nose, accompanied by warm sincere quiet praise, is a jackpot.
Kneeling down as she's brought toward U, or sitting in a chair or squatting, plus being SIDE-on
vs facing her, will reduce Ur size, perceived threat, & her anxiety - especially be aware of turning Ur gaze away
as she's brought to U via the drag, or comes to U [later in the process].
She cannot be left unsupervised wearing a drag, just in case it should snag - but when U're home, it's on.
Chis are smart & trainable - the sooner U begin, the faster U'll progress.
Please keep us posted? - thanks.