Lump On Back Of Neck. Painful, Tender To Touch, Size Increasing. Had Basal, Squamous Cell Scalp Cancer

Hi, I'm a 60 year old female with a history of basal cell and squamous cell scalp cancer. Thursday night I noticed a pea sized lump on the back of my neck well below the hair line. Within 24 hours it was the size of a marble. Now at 48 hours is a little larger and is no longer roundish, it is oval and extends beyond the middle of my neck. It was initially almost centered on the back of my neck. It was hard and painless to start and continues to be hard but a little tender to the touch. I made an appointment with a dermatologist for Monday afternoon but am concerned about the rapid evolution of this lump. Should I be in an ER? Thanks in advance for your thoughts.