Using customer toilets on shift

I felt really light headed just as I was finishing a shift so I thought best to quickly run into the customers disabled toilet to have a minute to take a few deep breaths and see if I would be sick which I was not in the end. Then a customer in a mobility scooter saw me leave and started telling me that I should of never used that toilet. I explained to her that I felt unwell, in response she shook her head and I walked away as she moved on. Will I get fired for this?