I Have Pimples/acne On Base Of Head, How To Get Rid Of These ?

I am a 35yr old man. I have been struggling with pimples/ acne in the back of my head for more then 5yrs. It is very itchy and bloody and yucky on and below the base of back hair line. It s like every hair grows with a pimple or acne and it s spreading to my head causing blisters. It is so very itchy that I kept scratching it causing it to grow even more. I ve been to doctors and they gave creams, ointments which seems to just kind of decreas the appearance of the pimples but when I finish that cream, pimples/acne all came back to life and it s killing me here. The collar of every shirt/t-shirt I wear has blood stains everytime I wear one. My wife complains as she changes pillow cases every now and then coz of the bloody stains on it. She even don t allow me to handle or cook food for us as my hands are disgusting from scratching my bloody head acne. I ve been told by a chinese dr that this cause from breathing toxic chemicals from previous factory work but I didn t take his tablets. So now I don t know what to do as I m hopeless that this pimple on the back of the head is gonna be there forever. Pleas help:-( Paul