Swollen Glands in neck when raise heart rate

[cesh]

When I run/raise my heart rate the lymph node in my neck swell and are extremely uncomfortable to the point of painful after about 5 minutes of doing any sort of strenuous activity.
I know this is not from an infection, this happens every time I exercise and raise my heart rate and has been occurring for over 3 years now (or longer, I am unsure).
I would like to begin training for a half marathon but find that if I attempt any type of running this problem occurs and I have to slow down to a walk to lower my heart rate so the swelling will go down.