I had something very similar to what you described but it was on my neck, something everybody would stare at when talking to me. It was about an inch and a half below my right ear lobe, about 2 cm. in size. Because it was causing nerve type pain when I would wash and run my hand over it (and if anybody has had nerve pain, they know how bad it feels, like electricity for me shooting up into my head, LOL.) I finally broke down and asked my doctor to refer me to a general surgeon. It was removed and biopsied and turned out to be a benign lipoma (NOT lymphoma. Big difference as those of us that have some medical knowledge know.). The reason it was causing pain is because it was growing up against a nerve, but not in the nerve. Lipomas, themselves, are usually painless unless they're pressing on a nerve like mine was.
Don't ever be too embarrassed to ask your doctor a question or have her/him take a look at something you have a question about, please...
I can laugh WITH you when you said, "My doctor thinks I've let nursing school go to my head, basically "thinking zebras when I hear hoof beats instead of horses" .....I have had the same doctor for over 12 years now. She is the type that you can joke around with, ask how she is doing, ask how her family is, what they did on their vacation, etc., etc.. She can also be very firm with you when needed, if needed. She has a fantastic 'bedside manner', the type of doctor I really like having. But she knows I have medical background, as well, so when I go in and start opening my mouth, LOL, she will roll her eyes in that joking way and smile or laugh and then agree with me a lot of the time. (Those of us with some type of medical background/knowledge can be the biggest 'pain in the butt' sometimes, depending on the doctor we have, but do not let that keep you from asking questions or anything at all.)
I hope all works out well for you. Good luck on Monday and if you can/want, give us an update when you can.
Take care......