Lumps behind Ear

Hi everyone, 

My girlfriend recently found two lumps behind her ear (lymph nodes ?), they've been there about 4/5 weeks. They're probably both just slightly larger than your average pea and right next to each other, almost connected. We've been using google and are obviously worried about cancer (me, mostly). She doesn't have any other symptoms like weight loss or fatigue. 
 

She saw her GP who didn't seem overly reassuring other than saying "I'd put my money on a cyst", she has been booked into an ultrasound but this is a few weeks away. 
 

What experience does anyone else have with swollen lumps behind the ear specifically?