That sounds really stressful! I'm with dogstar - it sounds like extreme anxiety? Maybe separation anxiety? Which can come on suddenly especially if it's prompted by a triggering noise/experience, especially if Sorcha has some prior anxiety experiences (or PTSD). I have known dogs who were on doggie prozac as a first step, and it was very helpful for them both because it made the dogs calmer/less afraid and because it helped their humans to be less stressed or fearful as well, so they stopped reinforcing each other's feelings. And if Sorcha were calmer, it might be easier to work with her in terms of behavioral solutions to anxiety? When you see the vet, if the vet doesn't find any pain or physical health issues that could be stressing her out, you could ask about anti-anxiety meds for dogs? Most are generic and not very expensive iirc.

It is so tough to have a dog who is freaked out, I'm so sorry you're dealing with that for weeks on end :(