How to teach a horse to run away from you. Skin condition in mare after loss of foal. Related?

I review Tuppy's skin and then add a video where I treat it.
Tuppy's skin condition got worse when her foal died. Her foal, Dyani, was 18 months when she died. Both she and Penny got sick after Dyani's death. Penny was Dyani's paddock mate and they were very close.
Interestingly the first time Tuppy went into the paddock that Dyani died in, she went straight to her grave and nibbled at the dirt.
These two horses are in the same conditions as the other horses and they had/continue to have significantly worse skin conditions, allergic reactions and itch, in Penny's case weigh loss, since Dyani's death.
Coincidence? Maybe.
I suspect their immune systems have been affected by the loss. Might be reading too much into it, it's an observation.