P.S. I thought of something else when I re-read your message. You mention those blisters and I had asked you whether your doc had checked you for staph aureus (it can cause folliculitis/inflammation of the follicles) and candida. But it would also be well worth checking for herpes simplex type 1 /HSV1 which is the cold sore virus, which can also be done with a swab from those pus filled blisters (the fluid in the blisters doesn't have to be clear to be HSV1, it can sometimes look like pus).
One more thing - that burning sensation at the back of your head - that might be occipital neuralgia or tension headache. If it is occipital neuralgia (which is common and gives a burning or stabbing sensation) - then the usual pain killers don't help and you could ask your doc for something that helps neuropathic pain (Endep or Lyrica).