Can I be written up for having to leave during an asthma attack?

I am a Front End Manager (Team Lead) at Walmart and have severe asthma.

Last Friday, I had an asthma attack while at work. Because of this, I informed my co-workers that I needed to immediately leave, as I did not have my inhaler with me. I handed my manager keys off to the service desk associate, instructing her to give the keys to the other front-end manager (who was currently on the phone) so she could hold them so I could go home to get my inhaler. At this time, I was expecting to go home, use my inhaler, and come back to work. This did not happen though. My asthma attack was so bad I had to stay home. I tried giving the keys to the other front end manager and even tried getting her attention, but I could not wait for her to get off the phone, as I had severe respiratory distress and not only could I barely breathe, but I was panicking due to not being able to breathe.

Come today (Tuesday), I was given a action level Red (a high-level write up) because I handed the keys off and left. I tried informing the store manager that I tried waiting for the other front end manager to get off the phone, and even tried getting her attention so she could hold my keys so I would not have to take them out of the store, as my initial intention was to return after my asthma symptoms subsided. However, the events turned and I unfortunately became so overcome with respiratory distress, panic, and desperate due to my medical emergency, that I handed them to the service desk associate instructing her: "Give these to the Customer Service Manager to hold on to and I will be right back after I get my inhaler. She will have to give them to a salaried member of management, because I can't wait since I can't breathe."

The store manager asked me: "Why didn't you just give them to a salaried member of management?"

I informed her: "Initially I was planning on returning to work after I got my inhaler. Due to the severe respiratory distress, and the anxiety and panic caused by this distress, I could not return to work and required a nebulizer treatment when I got home. Because of the decrease in my Blood O2 Saturation levels, I was probably not thinking clearly as well."

I was still given a red action code (which is just below being fired), despite my desperate measures that I took in a short time during severe medical emergency.

Can they write me up this severely when I was during a medical emergency? As I previously stated, I was planning on coming back to take care of my equipment but required much more medical treatment, leading me to not only take the rest of that day off, but the next day as well.