What would cause an itchy rash over a tender lymph node? havent scratched.

Check it out: See a doctor about this. There are many causes for a tender lymph node and this deserves to be checked out by a doctor. Often, the itchy rash can be caused by a fungus (scalp ring worm - aka tinea capitus) and the lymph node(s) nearby can become swollen and tender (lymphadenopathy). Sometimes the skin rash can be due to an allergic skin reaction and the lymph nodes can do the same thing.