Tender lymph nodes in neck with head pain/what is it?

Could be... A few different things. Tender is usually a good sign. If you have a few relatively small tender lymph nodes & you struggle with allergies or have a cold, those could cause it. However if you have a very lg node/nodes, it's best to get that checked out. You might also want to check for swollen lymph nodes elsewhere in the body & if you find some, that would be another reason to get checked out.