Thanks to our own
oneonthefence I'm looking at
this. Hoped to find a simple guide on how to check your own neck, but it seems you'll need a doctor to do it.
No doubt this was why my GP referred me to a cancer clinic when I reported swollen glands under my ears. For me, those are still mysterious (but made my recent mammogram painful) and I never really thought it was cancer, because it's equal on both sides.
Enough about me. If at all concerned, get a neck check.