I have this zit on my scalp which never goes away and it keeps popping every few days and i had it for few months now?

Have it cultured.: It may be nothing, but it also may be a bacteria that is resistant or deep enough in the pore to escape expungement. I would recommend having it cultured to make sure that it is not a bacteria that would require antibitoics. Hibacleanse is an over the counter topical cleansing agent that is strong enough to kill staph, you could also try that for a few weeks in the area that is affected.