My surgeon was a bit of a character and told me "I'd rather have my head shot off than have a pilonidal sinus surgery re-packed" -I elected for surgery. Open wound after debridement I believe, to be packed with sterile gauze as it healed. My partner, bless her, did the packing, something she'd rather forget too. Nurse wasn't up for it.
Sitz baths in plain old salty water were a delight.
Get it treated folks, especially if you travel for a living like I did: it usually won't go away by itself.
Alas mine was familial. My son poor bugger already has signs.