Thank you for your question.
From your research on the internet, it would certainly seem reasonable to discuss this further with your GP. Perhaps they will have information that supports their prescription and it might be worth deciding together what is best.
In terms of altitude sickness, the general advice is that you ascend slowly to limit the development of HAS. There are numerous international guidelines on ways to prevent it and in general the advice is to limit climbing to <500m per day.
There is an excellent guideline available from the UK NHS here.
It is also worth discussing with your guides as to what they have planned for you and if you are uncertain about your fitness, taking things easier might be best.
Good luck with your trip and have a great time!
BW
Dr Dinesh
