This is not uncommon at all when it comes to altitude. In addition to seeing many cases of altitude sickness, I have even seen someone who has been on Everest several times get pretty sick at 18K.The thing that is confusing me is how this seems to be "new". In my previous 14ers, which now numbers 50, this has never happened. All of my food, diet, health, physical conditioning, and acclimitization time are more or less identical.
Without arguing, I would politely disagree that it couldn't be related to altitude, unless it also happens at lower altitude. One test might be to really push yourself at a lower altitude, to same point as being exhausted and see if the symptoms are the same. If it also happens at lower altitude, then I would agree 100%.I'd rule out AMS because it's linked to physical stress not altitude
A doctor check is a good idea.
Not necessarily. Above a certain altitude (which is different for every person and even different for each people over time), the body produces certain hormones, such as the hormone leptin, which suppresses appetite. Although leptin is also produced at higher altitudes while at rest, and appetites are still lost at rest, production of the hormone increases with physical stress because the body attempts to maximize oxygen available to the brain instead of "wasting" valuable energy on things like digestion.key point being it stops when level out but are at the same altitude.
That said though, it would be much to go to a doctor and find out what is causing it. It could be a combination of many factors, including exhaustion (or something else not mentioned yet). Whatever happens, let us know!