I also get large painless spots just under my hairline and in other isolated areas on my neck. They also generally take ages to fully disappear.
But the two things I have found that helps are -
a) avoid dairy. Especially chocolate & sugary dairy drinks. Maybe it's just a personal thing but I nearly always get flare-ups when I eat these items a lot.
b) try using turmeric cream to treat the affected area. I find it really helps to disinfect the pore and relieves swelling. It also works a wonder on facial pimples and infected cuts. Can be purchased online quite easily
Hope this