Massive painful pimple on back of neck ?

First, make sure that it’s ready to be popped.  Have someone help you remove it.  They should be able to see a clear head, where you can see pus.  If it appears ready, you can make it easier to get out by placing a warm, wet towel over it multiple times a day.  You could also just get a sore pimple gel from the store, and let it go away on its own.  

May be an abscess that should be seen

Get a close friend or relative to do it.  They can numb the area with ice first, then disinfect afterwards.  Or, just leave it alone, and tough it out for a day or two.