I wanted to share the solution that finally worked for me. I've been plagued by acne on my head and neck for the past year, it started for no apparent reason that I could see.
I tried anti dandruff shampoo, showering twice a day, changing my diet, etc. and no dice. Everything I read said the problem could be fungal, bacterial or other so I decided to just try a shampoo that was both antibacterial and antifungal, within a week the spots and lumps on my head cleared up - I'm well pleased and it turned out to be pretty cheap too (£8.20 for a very concentrated bottle), it's available from Amazon in the UK:
http://amzn.to/12UP0Ck (£8.20 for 150ml)
http://amzn.to/12UNMXG (£20.15 for 500ml)
I'd recommend trying the smaller bottle first to see if it works
I tried to find it on the Amazon in the states but it doesn't seem to be for sale, I even tried to find a substitute based on the active ingredients but no luck so I suspect they aren't allow in the U.S. or use a different name.
Good luck and I hope it works for you