Welome to HCM
We understand your concerns
I went through your concerns. I suppose the heat outside is taking its toll. The problems and symptoms you are facing are typical to hot climate. From the description, I conclude that you are not that familiar with hot climate. You are forced to drink more water due to the dehydration
and therefore you lose apetite as the apetiser juices produced by the stomach organs are diluted again and again. This is also healthy in a way. This diluted liquids induces acidity and hence nausea
. Nausea should happen whenever you are moving or working in the afternoon, no relation with being outside but certainly have relation with work and being in hot sun.
Take rest for two days and you should feel better.
Hope this answers your query. Available for further clarifications.