These sound more like nodules to me than papules. You might try going to a derm who does cosmetic surgeries and see if the spots can be extracted. Sometimes the core of the pimple is so deep under the skin, that the spot just won't heal all the way. I have only ever had one of these - a pea-sized lump that was way under the skin on my jawline. It just stayed dormant on my jawline for a few months. I had it extracted by a cosmetic surgeon and it went away and hasn't come back.
Hm, this could be more serious than I thought.
The thing is, I don't get "regular" acne--I rarely get whiteheads and I never have had a blackhead. But I get about 1-3 of these weird papules/cysts/nodules spots a month. Mine are usually around a uniform 5mm. I could never figure out if it was a papule or a cyst or whatever. It sucks because my skin is usually decent but I'll have a huge single zit that is incredibly noticeable.
Now that I have figured out what they are, any suggestions on prevention/treatment?
Also, since I get these pretty frequently, it'd be pretty expensive to go to a derm every month to get them extracted..
From the pic you posted it doesn't look like a nodule. It looks like its right at the surface of your skin. How long have you had it? Nodules are ususally deeper under the skin. That looks more like a pustule to me. You said you get these frequently? How long do they generally last?
If you don't think extractions are an option for you, then you might try a couple things. Both ice or heat can help in different ways. Ice can help reduce redness and swelling of a pimple - you can ice it 2-3 times a day for 5 min or so each time. A warm compress (you can add salt to this too) may help bring it to a head. Apply a cotton ball or washcloth that is soaked in very warm water to the pimple until the cloth cools off, then dip it back in the water and repeat. This method works for some people to bring spots to a head quicker. Just be warned that it might make the spot redder at first, so don't do it right before you are going out.