So that may be the difference here, because I have a septum deviation, which means that my nose is permanently somewhat stuffed. But when I have temperature and feel sick, I absolutely go to the doctor every time. There's a few things that a doctor can do and I can't that can distinguish between "just a cold" and something more serious. For example, I cannot look into my own throat or into my own ears.

Your other comments indicate to me that this may be a cultural difference though. In Germany, it's normal to ask a coworker who appears to be sick to go to the doctor. Everywhere I've worked so far, there's a shared awareness that working while sick is a huge cost on the entire team. That goes for managers, too: They know that when e.g. a workplace accident happens and the person causing it was sick, the insurances are going to be asking a lot of uncomfortable questions.