I’m 18 Years Old And Not On Any Medication And

I’m 18 years old and not on any medication and am overall healthy. I live in Florida and was working outside all day when I experienced heat exhaustion. I drank about 30 ounces of Gatorade when I felt sick but a few hours later I vomited all the fluids I drank. I was curious as to why we vomit if our bodies are trying to replenish themselves isn’t that counterproductive?