Large pimple won't go away...

I've had this huge pimple on my back for months, maybe even a year.  I got it to pop and tons came out, but it would refill every few days.  I started washing it with a oil control body wash and I think I even put salicylic acid on it for a while.  Anyways that was all months ago.  Now it is still a large raised bump, the size of a eraser maybe.  It is not red nor does it have a white head.  It isn't painful, but I kind of would like to get rid of it.

It isn't a cyst or anything else, is it?  Any help would be much appreciated!

Thanks!

[JGF25]

It definitely could be a cyst.  Even when you lance a cyst, you have to get all of the pus out or it will simply come back.  If it is bothering you, then a trip to the dermatologist is in order.