Constant fatigue, overactive mucus production, slight headache, difficulty focusing, productive cough (mostly clear mucus), and slight left ear pain. what could be causing these symptoms? i do not have allergies?

Typical symptoms of viral upper respiratory infection (common cold) but Covid-19 infection needs to be ruled out if you are at risk. You can take OTC meds such as Tylenol or Motrin + Mucinex DM for those symptoms. You are young so you should be fine in case you are at risk for Covid-19; however, testing should be done to protect the unvaccinated people around you.