Treatment depends on the grade..Acne or  pimples... Due to hormonal changes..Oily skin causes it...Common in adolescent age...May occur in adults also.. Food like Oily foods, ice cream, chocolate and sweets increase it.. Treatment depends on the grade of pimples or acne..So, please  send photos by direct online consultation as it's a must to see which grade of pimples or acne for accurate diagnosis and treatment.

The problem that you are facing is Chronic scalp folliculitis Requires long term antibiotics Also we need to find out the cause for same? Is it just below the hair line in the back ? Change your pillow cover often , keep your nails trimmed , keep your combs clean This is usually a mixed infection so need proper treatment not on and off drugs

Get your CBC and blood glucose levels checked. Keep your hairs short or near bald. Recurrent folliculitis is due to more sweating , poor hygiene etc...