I had a sudden onset of this same symptoms (very painful lumps on scalp) and it turned out it was herpes zoster (a nerve inflammation provoked by the varicella virus). You might want to consider this possibility...
I'm sorry to hear of your troubles as well. Unfortunately I don't expect much to be found either.It all just seems to center around this 1 bump and has now snowballed like yours. I am dragging my husband to the dr's today so I will be sure to let you know. Good luck and thanks for all who replied.
I have this same thing- just started on Saturday. I think I am going to a Dr. about it- and I hate going to doctors. Sounds like this is a mystery to them. Also I had stitches 3 weeks ago and was on preventative antibiotics. I have read some others on other posts that had just come off antibiotics. Anyone else? Also I have swollen eyelid (just figured it was a stye) and some red bite-like bumps over my left eyebrow. Also for me this seems to be spreading from a spot on the left side of my head.
Sadly I don't hold out much hope getting a clear answer on this.
From a home gamer:
Doesn't sound bad enough to see a Dr. yet -unless you have great insurance and want to kill some time. Try talking to a pharmacist, they are very helpful in recommending over-the-counter topical treatments. Try a different shampoo, something like T-Gel or Selsun Blue - these may take a week to work (if they work) but the tingling may subside with use and therefore help to keep him from touching it so it may heal on its' own.
YMMV