It is very possible that you have two diseases at the same time. Get four signs that the virus you caught is actually two (if not more) If you seem to be feeling better, and suddenly the fever rises, the nose doesn't stop running, the cough becomes more severe and you are tired most of the day - all these can be an indication that you experienced a bacterial infection during or immediately after a viral illness.
After your body fights significant viruses such as corona, flu, RSV or even a severe cold, it is much weaker and vulnerable.