What Causes Lump Behind The Ear And Swelling In The Neck?

Took a shower the night before and woke up with a golf ball size lump behind my left ear. Later on my left lymph node (neck) swelled. At the end of the day I had red hard bumps all over my scalp. My boyfriend said they look like pimples. These all just showed up out of nowhere. Do I need to go to the ER or can I wait until Monday for urgent care?