Your lymph nodes are located
in your
neck underneath the jaw, above the collar bones, underneath your armpits, In the back of your knees, and near the groin where the stomach crease meets your thighs. There's more but those are the big ones.
Anytime your body is experiencing an infection your lymph nodes will flare up. Strep throat, colds, and sinus infections/irritations also have a lot to do with lymph nodes swelling.