I was up in front of a disciplinary at one of my past jobs for having a greater than average sickness record. I'd had 20 days in a year, and they only allowed for 12. In short, I'd seen their occupational doctor when I joined, who had said I would probably need more sickness leave than average and they should support me; a large chunk of the sickness leave had been in my probation period (flu with a chest infection) and they'd passed me after probation without mentioning it; and then a few months down the line suddenly it was a disciplinary issue! I got my union rep to come to the meeting and he said he'd never seen anything like it in his life. HR said they believed my sickness was genuine, but they believed that disciplining me for it would help it to reduce. Also that they wanted me to get a certificate for every day of absence in future which they also thought would help (although all my past absences were certificated in any case). They also docked my pay to compensate them for the days I'd had, even though they were genuine, supported by their own doctor, and fully certificated by mine. Absolute bollocks. I was fuming too. I left that company as soon as I could. I'm sorry you're getting the same kind of shit, especially given the nature of your job where you could easily be assaulted or injured, and where you come into contact with all kinds of infectious illness! I think all you can do is put up with it or leave, sadly. If they are unreasonable about it now, they probably won't be any more reasonable later.