Here in middle earth we have some pretty strong labor laws. For the context of this, everyone who works for a wage is given ten sick days per year. These are paid as normal. Additionally, if your employer asks you to get a medical certificate for any less than three days, they must pay for it.
I called in on Friday as I was feeling a bit shit, the job had been bringing me down and the manglers are fuckwits of the highest order. As well as a lack of sleep and other pressures
A few hours later my manager called and asked for a medical certificate. Worked for me, I needed to visit the doctor anyway. Popped into the doctor, waited a couple of hours to be seen and had a chat. Doctor was pissed because I was wasting their time for some bullshit, powertripping manager so she flat out asked if I wanted more time off. I wasn't going to say no to an offer like that so I ended up with the following Monday to Friday off too.
We had a full thirty minute slot, so I actually got a bunch of other stuff sorted and some new medications going. My favorite part: I'm enrolled in this particular practice so a doctors visit is usually about $45. The doctor confirmed that my workplace was paying so she added a bunch of fees and other shit. Made the bill closer to $500. Eh, I'm not paying for it.
There was extreme levels of snark when I emailed the receipt and medical certificate. Got a phone call from my mate saying my manager had lost her shit. So now it's Saturday night and I'm watching some LOTR and having a beer knowing I have still more than a week off.
TL:DR: Take as many sick days as legally possible. Managers don't care about your mental/physical health and expect you to waste time proving you're sick.