After many years of visiting high altitudes, I began experiencing altitude sickness. It was similar to what you are describing. I tried oxygen and got minor relief. A sports medicine md in Crested Butte suggested acetazolamide (Diamox). That worked for me. It is taken beginning 48 to 72 hours prior to assent to altitude. I continued to take it for the next three days. After that, hydration, sleep and no alcohol to stay symption free.
After much research, I can to the conclusion that a change in blood pressure medicine was the root cause. Several years later, I changed BP medicine. On my next trip, I didn't use acetazolamide (Diamox) and was symptom free.
This is a serious condition and requires medical advice. I am sharing my experience, because most doctors are not familiar with altitude sickness and how to prevent it. Diamox must be started prior to ascent. It will not help once symptoms appear. Hope this helps