my son has the same thing! the doctor said it would go away on it's own but never did! it is spreading now!!!
my 4 year old daughter has these bumps all on the inside of her thighs and creases in her knees..... the doctor told me it was a virus and started with an "m" i wanted to do more research on this but i cant remember what it was called. he said the only cure is to freeze them off
It sounds like the spot on the base of your spine was a pilonidal cyst. Because you said it spread some, check out a dermatology website about hidradenitis suppurativa. I had to eventually have the cyst and the 'sack' removed from my tailbone and have had several more crop up - some on the insides of my thighs - and a couple under my breasts. Hope this helps. If anything crops up again, I find that warm compresses help to take the soreness out - and even using hot compresses can help bring them to a head and help them drain. I still end up at the docs getting antibiotics most of the time. I have been known to carry fever with mine as well.
Good Luck.
Sounds like you have MRSA