I have a hard lump behind my right ear. it's also red and swollen. i also had a rash on my back of my neck yesterday that was red and bumpy.

Suspect cellulitis: i am concerned about your symptoms. This should be evaluated urgently and you may need antibiotics. If you had a more gradual onset of symptoms this could also be serious. Either way you need to see a doctor within 24 hours. Mark off the red area with a pen. If you see it enlarging quickly you may need a more urgent attention.