I had a similar experience. To add to it, I note that the environment and weather had nothing to do with it as I had lived in that situation before in other countries.
The difference is the people, not the “location”. Or in my case the inability to get away from the family and people, having to interact with people who don’t fully understand you, etc.
Very draining to say the least. Could not wait to get out of there after a few days. It seemed to sap my energy and I was very tired. I kept going on long walks alone, coming back to find the neighbors, uncles there waiting. They never seemed to “go away” into their homes, like they needed to be around you the entire time.
Sorry if this sounds negative on Thai people. Just my experience.