This. ^ it's such a horrible workplace practice, and makes the workplace such a horrible place to be when you know you cannot have more than three days off sick in three months, lest you get some kind of warning, (written warning even!)
I have been ill three times since the beginning of November and I've been kicked off my feet for between 3/4 days, and 10 days each time. Hadn't been ill/had a day off sick since 2017 before that, but still.. THIS time around, it was 3 sicknesses in 3 months. I'm very fortunate that I work from home and I arrange all my own workload, and am very independent. And I have to get certain amounts of work in by the end of any given month, so we have a very, very, very flexible work situation, as I can catch up quite quickly.
DH has been at his workplace for 20 years. He has a fairly flexible workplace too. Very kind and considerate manager and three or four colleagues who are more than happy to cover for the extra money - and it's just as well because he's had one thing after another for the last three or four years and he has had quite a lot of time off. He is nearly 60 and has had more time off sick since 2018 than he had in the previous 15 years!
We will both be glad when we retire... (in a couple of years,) to be honest with you. So we can just chill, lie in bed till 11:00 AM, go for walks, go for pub lunches, go out on daytrips, visit family and friends, and basically do fuck all if we want.
I think the workplace these days is much more stressful than when I started work in the early 1980s... You have to meet goals, you have to meet targets, you have to keep 'improving' and bettering yourself with stupid training courses that teach you what you already fucking know! And you can't have more than five or six days off in a year, or you're a 'skiver,' and 'everyone's had to pick up the slack,' and you get a scolding! As if you WANT to be fucking ill. FFS!!! 
I swear to God, it never used to be like this when I started work 40 years ago. And there didn't seem to be the massive levels of stress then. I mean that causes people to be off/to have time off... The stress work puts on you (in many work places, not all,) is going to make you feel mentally run down, which will make physically ill. To be honest with you, I start looking for another job, maybe something with more flexible hours. Take care @Stuckinthemiddle1990 