High altitude sickness can be debilitating. On a steep mountain like that it would take at least two other people to lower one on a rope if they were completely disabled. One on top and one at the bottom of each rope pitch.
I used to be a mountaineering instructor with the Colorado Mountain Club. I dealt with altitude sickness there, but never by myself. We did do winter ascents of 14,000 ft peaks, almost always without incidents because we always had enough people to do a rescue.
When I climbed Cerro Aconcagua in the Andes (photos on my home page) we expected to have a frozen body at the summit. The body had been there for years, but it was not really possible for humans to get it down. I am guessing that someone rolled the body off the edge and down the south face. We had a team of ten and seven made it to the summit. Two were having altitude problems at the nearly 23,000 ft summit. I was the second most experienced climber in the summit group and I was chosen to get the sickest person down to high camp (about 19,000 ft) as fast as possible. The most experienced climber worked the ropes for the other group of five including the other person with slightly less severe altitude sickness. The person I was working with was really sick and just wanted to sit down, but was able to do rope work on each pitch. The summit day took about 19 hours from high camp and back, but everyone made it. In the two month climbing window in December and January that season, I think 6 or 7 people died on the mountain, all from altitude issues (pulmonary edema and cerebral edema).
Going to 12,000 ft without acclimation can also be deadly.
Years ago we would make two trips a year to high country backpacking and climbing fourteeners. I was in great shape back then but one trip I got altitude sickness even though we were not all that high. Nobody else suffered. It is a very sick sick.
Thanks. Based on your photos, it looks like you climbed Aconcagua around 2012 or so.