I am really sorry about your health issues and know how strict the policies can be, as I was a HCP for years.
During that time, all the women on shift at one point or another either shat themselves, had a period which flooded or were covered in vomit.
It would have been unthinkable to just walk out of work without telling anyone we were going. Working with vulnerable people, and strict staffing ratios is important.
You work in care. You know people have accidents. It is normal. You know no-one laughs and takes the piss.
You could have gone to the work loo and shouted for help, or pulled the alarm cord if needs be. Other staff would have come, and could then have helped you out the building, but at least they would have known you had gone.
Also, if you are having investigations, you do not know at this point that what you have is not contagious. You would only know that if any patients in the care home caught it. By which time it is too late.
Let your boss make the decision on whether you should remain off for 48 hours. Then it is not on your head. If you go back, against policy, and spread it, then the outcome would not be good for you or your residents.
Would I discipline you for this? I would HAVE to. No choice I am afraid. I couldn't risk losing my job because I didn't report and discipline a member of staff for leaving without telling anyone.
I am so sorry.