Welcome to HCM
We understand your concerns
I went through your problem description. I suggest you not to worry too much. Your assumption could be right. The nauseating feeling could be from the fumes in the yard. Or you are sick of the sunlight and overwork and climate or you have food poisoning
due to the food you ate the day before.
To conclude, drink lot of water and wait a watch. If this repeats in normal environment, it should be food poison. Should consult a physician if this goes on for two days.
Hope this provides you with an answer. Available for further clarifictions.
Good luck. Get well soon.