What sickness is going around?

Lately, I’ve noticed several coworkers and acquaintances mentioning they’ve been sick, with one specifically mentioning pneumonia. I’ve recently come down with symptoms myself, including a headache, congestion, sore throat, coughing up phlegm, and now body aches. Naturally, my first thought was COVID, but I just took a COVID and flu test, and both came back negative.

I’m curious: what illnesses are currently going around in the area? Has anyone else experienced similar symptoms but tested negative for COVID and flu? I’m baffled and trying to figure out what this could be.