Elcus? What the hell is elcus?

yes, it was. he's been operated for stomach ulcer and he also had ulcers on his legs. and no, a hungarian dictionary doesn't help...

At the start of the film his current problem -the reason he was nauseous and didn't feel well and called the ambulance- was tumors (neoplasms) on his liver. They're likely cancerous (nobody knows for sure because no biopsy has been done yet), and likely terminal in the next few months. The nurse initially suspected colon cancer, which was pretty close to the correct diagnosis; the second part of the CT scan confirmed the presence of the tumors.

(One of the later doctors though argued the X-Rays had been misread, that what looked like tumors were really just "abnormal structures". [Disagreement on whether an X-Ray shows cancer or abnormal structures is reasonably common - they can look very much alike.] In the context of the film it doesn't matter at the moment though; the acute problem requiring immediate operation is the "sub-dural hematoma" [the bleeding inside the head], not the probable tumors.)

The leg ulcers didn't help, but weren't the problem. The stomach ulcer he had treated 14 years ago (no connection to "leg ulcer" except it's the same word in English) was a suspect in his complaint, both because it was in approximately the same place as the current pain and because it was expected that his drinking alcohol had exacerbated it. It too didn't help, but in the end it too wasn't the problem.

When he was in the bathroom in his apartment as the ambulance first arrived, he fell into his own bathtub. Nobody thought much of it at the time. But he'd bumped his head hard enough to cause life-threatening internal bleeding. That was the "sub-dural hematoma" ("SDH") that became the primary issue. It first showed up clearly on the CT scan of his head. It was also why there was lots of talk about "neurology", and why some otherwise-unusual diagnostic procedures (like "squeeze my hands") were used. It was why he progressively lost his speech and eventually became unconscious. That's why the talk about "drilling his head", and that's what his eventual surgery was intended to address.

Other than some of the doctors commenting that it might be a bit silly to operate to treat the SDH only to have him die of cancer a few months later, the original problem didn't even seem to be mentioned in the latter part of the film.