Earlier quoted context omitted.
Even better: Sick days shouldn't be a pool at all. In Norway there's X amount of sick days one can use without any hassle (all paid), to use any more all you have to do is show a doctors note. If you have to use more than Y amount of days (chronic illness, a more serious thing or something), the government will temporarily take on the responsibility of paying the worker's wages. I don't think people should be punishe…
In Poland the number of sick days is unlimited but you need a form filled by an actual MD in order to claim it. Vacation days are separate pool.
If you said you were (still) sick for 3+ days you'd need some kind of doctor's note. Though these are easy to receive - the hardest part is usually getting an appointment in a hurry.