Rude manager humiliating a sick person

I am terminally ill with double heart failure, including pulmonary hypertension, emphysema complicated by Addison's disease, pulmonary emboli and Systemic Lupus. At the best times, I battle to breathe and feel as if I am suffocating. Cloth masks severely restrict the amount of oxygen and I quickly feel faint wearing one. As per the Government Gazette, a "face mask" is a cloth mask, a home made item that covers the nose and mouth or another appropriate item to cover the nose and mouth. The WHO describes a plastic/see through mask as one going around the face and extending below the chin. I was at the Dis-Chem Kolonnade today with a plastic mask (not shield) on. The security wouldn't even listen to why I opt for the plastic mask, he rudely said that he would call the manager. I politely asked him to listen, but he said I could speak to the manager. As she approached me, she already said something to the effect that "we were not going to have problems". It wasn't my intention to be difficult - suffocating is not an unreasonable request to beg an augdience for. I tried to explain to her my medical condition, and she sarcastically told me that "all the people who come into Dis-Chem were terminally sick". When I told her what the regulations say, she told me she also has the government gazette (which obviously she was disregarding) and offered to sell me a medical mask. I tried again to explain that I felt faint with those masks and to me, it poses a serious health risk. I already suffered a stroke March 2020, as part of complications. I almost begged her to listen as I have no other option to go to Dis-Chem myself and to please consider my health. But apparently only Covid is a recognised disease. All other illnesses are disregarded and it doesn't matter how you suffer. They don't care if you can't breathe. She was extremely rude, making a huge fuss. She then said "we are done arguing" - but I never argued. All I wanted was to breathe. I did all I could to keep from bursting into tears/ Life is so hard in my condition. But she did nat even have an inch of sympathy. I then told her, that I would put on a cloth mask, but will be pulling it away from my face so I could breathe. To this, she did NOT OBJECT/ What is the purpose then? I would be breathing out the top of the mask, wheres with the plastic mask is went out at the bottom - but would still stop virus particles. My complaint is the absolute callousness and complete lack of empathy and decency that this manager subjected me to. She made me feel as if I was a trouble-maker, just because I wanted enough oxygen supply. I can't remember when last I was this humiliated.