I may have had something similar a couple months ago. Came back from trade show in Vegas with a the start of a very bad respiratory infection.
Ended up similar to the Flu: fever, BAD rattling painful cough, sweats, pain etc. But no throwing up or digestive issues. Wife wanted to take me to the hospital as I was sicker than she's ever seen but I said no. 3 days later I was finally vertical, barely.
Don't know what it was, wasn't the flu, way beyond bronchitis.
I was not the only one to catch this at the show.
There were a lot of foreign nationals at the show, which means nothing except the powers that be say this Covid came from Asia.