Now with replies enabled...
Had she recently been given Covid jab?
I got heat stroke or heat exhaustion in my early 20s when I took a job mowing grass at an apartment complex. Turned out to be up and down hills with a push mower.
I wanted to show ‘em I could do it and forgot to drink water. Took a couple days to recover so that was the end of that job.
Note: Symptoms - What to Do (heat related illnesses)
https://www.cdc.gov/disasters/extremeheat/warning.html#text
More about symptoms...
https://www.mayoclinic.org/diseases-conditions/heat-stroke/symptoms-causes/syc-20353581
https://www.mayoclinic.org/diseases-conditions/heat-exhaustion/symptoms-causes/syc-20373250