Recurring external blood blister behind ear lobe

Can someone please help me diagnose and suggest treatment for my problem:

I have been getting a recurring blister behind my left ear lobe. Had it for past 4~5 years. Starts small and grows to about a small marble size. Develop pain during later stages when its about to burst. At that time I can feel enlarged painful node on the side of my neck under the ear lobe. No pain in the ear or any problems hearing.

Went to emergency couple of times, when it was big, before it broke. They did I&D (incise & drain), but it comes again. When it broke by itself I observed mainly blood, and some puss come out. There is also a white discharge which smells really bad coming out of small pore by the side of the blister when pressed. This discharge appears before the blister breaks. Once most of the liquid inside the boil is drained, it will stay down but does not entirely go away.

Frequency of recurrence maybe about twice or thrice a year.