I'm dissenting with everyone else here. She was rude. I wish you had puked in the store then she would have gotten what she deserved.
I don't see any way in which the salesgirl was rude. She explained they didn't have a bathroom, she suggested where the OP might be able to find one, and explained that the changing room couldn't be held in the meantime. I didn't see any indication that she did this in some kind of rude way -- aggressively or condescendingly. Why should she deserve to be confronted by someone vomiting? She didn't make the policy. The suggestion that this would be "deserved" is utterly offensive.
The Op said they could hold it "for two minutes" -- I don't know in what alternative space-time dimension someone can go out to find a washroom, be sick, get oneself back together, and get back in two minutes. I think it is outrageous of the OP to feel that everyone else in the store who is waiting for a dressing room should be inconvenienced.
This wasn't a random situation. It was a medical illness. I think that should be an exception and she should have let you use the bathroom.
If she had actually been overcome and vomited suddenly, they would likely have been perfectly understanding. Given that she was simply claiming to be unwell, and obviously did have time to reach the other facilities, this hardly seemed like a medical emergency. I imagine that in an average day there are plenty of people who would see themselves as an exception for one reason or another.
I wasnt claiming to be sick, I was sick. I basically took off there shirt so they wouldnt try to get me for stealing, and ran next door, in my shirt which was the only thing I had time to put on in the freezing cold, to use their bathroom, i had to come back to the other store to get my stuff which i had left there.
The line was short at the time and moving steady. No outrage here that they could remove the stuff from the dressing room and then just let me go in the next on available when I got back or something considerate. But whatever because I dont appreciate being flamed for little insignificant things.