Swollen lymph node

Last night I felt a small bump at the base of my skull close to my left ear. It felt tender to the touch but I can't be too sure of its size, maybe just under 1cm. I don't have any other symptoms, and I haven't been sick recently. I am a teacher and so I work around sick children quite often. I'm about 9weeks pregnant and my blood work shows that I am not immune to Rubella. So I'm quite nervous about any unusual thing happening to my body. Has this happened to anyone and it turned out to be nothing serious? I am happy to go to the Dr this morning, was just interested to know if this is familiar to anyone else and what it turned out to be.