No, your body cannot forget how to be sick, for a start it's not your body but the autonomic system (controlled by your unconscious mind, mostly out of your entire control) in a way, we as humans owe our very lives to this fantastic survival mechanism, think of it, you're a cave woman/man and you try to eat a plant that looks quite delicious but it has a poisonous element to it, you eat it, then your clever stomach detects a dangerous compound and then decides the quickest exit from your body, it convulses your stomach, and out it comes, saving your life!!!
As for being sick curing you, i'm not saying it's impossible, but I kinda doubt it, but maybe proving that it aint that bad, and, what was all the fuss about may help, who knows?
Look, if you are going to be sick, wherever you are and whatever the facilities around you, you'll just be sick, and frankly there isn't a damned thing you can do about it, so you might just as well just get on with life as best you can knowing this is natural, not only not deadly but a possible life saver. Heaven knows I understand as I have cured emets numerous times but not by stopping the response (I can't do that anyway) but leaving a kind of acceptance of natures disposal system!
Do you mind telling what happened when you were 5, I may have a suggestion for you, to help.
best wishes.