I'm no medical expert, and I think if it concerns you, a trip to the doctor is warranted. Calcified lymph nodes are usually caused by an old, inactive infection or some type of mineral imbalance. If it suddenly becomes painful again, there is the possibility of an infection. Have the doctor run a blood count to check for infection, and it wouldn't hurt to have your calcium and vitamin D levels checked as well (imbalances of these minerals are known to cause calcification). Finally, have them check for mono (yes, adults can get it too and not just from kissing!) - because mono requires a special test and doesn't show up in routine blood test results. Good luck!