@yvonne55 I can see why you are concerned! It is best to look at trends, not a one-time test result. Indeed, dehydration could have played a part in the eGFR change. Likewise, lingering effects of your illness, medications you might be on/recently stopped, even a change in the laboratory processing the blood samples can all be a factor.

It's not unusual for our gp to not be well-versed in kidney issues. Following a healthy diet, moderate exercise, reducing your stress as much as you can will go a long way to easing your mind. I would suggest you follow your gp's thoughts, and retest in a month.
Ginger