Hi,
As mentioned from the other post, this could be inflammation of hair follicles or folliculitis which often present with rash, pimples or pustules near a hair follicle in the neck and other parts of the body. The pimples may crust over and eventually go away. Topical antibacterial medications and warm compresses may help. However, if it persists, it is best that you have this checked by your doctor for proper evaluation. Direct clinical examination is important., Take care and regards.
Oh yeah and also. It's like an inch apart from my hairline.
Oh yeah I forgot!! Can you even get pimples on the back of your head??