Dear Dr. Kathrynne,
Thank you for your advise.
In fact dehydration is prevented if I have to rest at home a few days instead I go outdoor in the heated weather in order to adapt the changes of the climate from Cold to HOT.
As I was outdoor shopping in the winter I did not feel thirsty and less drinking for the past of three weeks from London,Paris,Rome and Spain.
Besides there were at different altitude when I flying back. I was from Higher altitudes to low and there is less oxygen available, and until your body adapts, it can result in weakness, shortness of breath, or dizziness.
It sounds as though you have found your own answer, congratulations.
Kathrynne Holden, MS