Mouth ulcers?

Has the doctor cultured these ulcers to rule out something fungal?

Supplement her caloric intake with something like boost or ensure and let her have as much as she wants of anything that she finds easier to eat, now is not the time to worry about a balance diet.

Did the doctor give ANY suggestions for treatment of the ulcers?

Has she tried gargling with warm salt water or rinsing with a painkilling mouthwash such as Chloroseptic?

Scoping her is an excellent idea; they will numb her throat so she wont feel the scope and she can be given a med to calm her. Be sure to request this.

My mom had this problem. The scope showed a narrowing of her esophogus and the treatment propsed was to stretch it using metal dialtors over the course of several weeks. I asked the GI doc if he would subject HIS 93 year old demented mom to this and his response was "He## no".

He referred mom to a speech language pathologist for swallowing techniques and we modified her diet to chopped food.

Definietly worth a scoping and biopsy. If it's something fungal it's easily treatable with either systemic or topical medication (liquid that you slosh in mouth and then swallow). If it's oral herpes ("cold sores") there's antiviral medication for that. And if esophagus dilation is needed, it can be done at the same time as scoping via balloon. The scoping can be done using light anesthesia, so she won't feel a thing. Mouth ulcers are super painful, so the sooner she can get treated the better. From the description, it sounds as though these sores are also in her throat and esophagus, contrbuting to the sensation of the throat closing. Even if the scoping isn't done, she should at least have biopsy done for the mouth sores to see what the treatment might be; I think there's blood work that can be done to determine if it's the herpes virus

This sounds like allergic reaction. What medications is she on; have the doctors posed any sort of suggestions as to what this is. Does she have auto-immune issues or is she on any medications that could suppress the immune system (allegy inhalers, corticosteroids, anything at all). It sounds dangerous with the swelling and frightening, and it is honestly necessary to follow some medical advice to see why this is happening because I am certain doctors have told you that this angioneurotic edema CAN cause death if the throat does close. We see this sort of thing commonly with chemotherapy.
I will leave you to the hands of the medical community where I am certain she poses a mystery they are themselves desperate to figure out. It is likely crucial now for them to know what portion of the body has these ulcers, something they can ONLY see with a scope. She will be mildly medicated for this procedure so try to reassure her. No medical procedure is done without some risk, but right now the risk of missing a diagnosis if much more real and much more scary.
I sure wish you both the best and hope you'll update us.