small red dots, what might be causing my rash?

last summar I started having red spots all over my back and shoulders and arms. It got worse and then it got better, but over the past year and a half it has never gone away

I have gone to the derm/doc 4 times for this. in the order of diagnosis:

a) first derm said it was folliculitis

b) doc said it was also folliculitis and proscribed me doxycycline as an antibiotic to treat it, it got much better but never went away.

c) derm then said it was just acne. lame.

d) derm said they couldn't tell for sure.

but needless to say, its still hanging around, actually, its spreading- now I have it on my neck and face. I thought I might as well also ask the internet- here is a (non graphic) image I took of my neck. http://i.imgur.com/fXemrV7.jpg

please, any ideas would be great, thanks!