In some very rare cases, the skin reacts to dermarolling by developing whiteheads. They will disappear. But it seems your skin reacted really badly to the 1.5 mm size.
I remember you posted here that your skin reacted "violently" to a 0.2 mm dermaroller.
To speed up healing, apply Neosporin antibiotic cream. It is sold OTC. Apply the antibiotic cream every 4 hours (not at night) for at least 7 days.
https://http://en.wikipedia.org/wiki/NeosporinIn addition, you can buy Betadine liquid (it is an OTC disinfectant) and apply it on the cheek for half an hour. Then wash it off with tap water.
There is always an immune system reaction after dermarolling. You can read more here:
https://http://forums.owndoc.com/dermarolling-microneedling/how-long-does-the-inflammation-stage-lasts-after-rolling-with-long-needles/In your case, roll or stamp just a small part of your face (not more than one cheek) and when it heals, do another cheek etc.
Disinfecting the dermaneedling instrument after dermarolling is more important than disinfecting the skin before dermarolling. Of prime importance is to clean the instrument after dermaneedling with dishwashing detergent and warm water (not boiling water) and rinsing it under a strong stream of water to remove blood and skin detrius from the needles. Then soak it in Chloramine-T or Ethanol. This prevents the formation of potentially harmful bacteria while the instrument is not used. The bacteria on your skin are much less dangerous that what can form when you don't clean a dermaneedling instrument.
Basically, if you do not clean a dermaroller, what forms on the roller head and needles are the same bacteria as that in a rotting corpse. Whereas the bacteria on the skin are totally different bacteria, it's more of a stabile ecosystem of probiotic bacteria, a protective layer of beneficial bacteria on your skin, a great majority of beneficial bacteria that prevent bad bacteria and harmful fungi from getting a foothold.
Your immune system has plenty of antibodies against the bacteria on your skin, aquired whenever you cut or chafed yourself. The same goes for active acne. Every time you squeeze a pimple, some bacteria enter your bloodstream and you make antibodies against them. Therefore, even if you "roll in" a lot of bacteria from your skin, there is only a very tiny chance that an infection can result.
So the main thing is to clean your roller after use with water and dishwashing liquid, to get rid of the "big chunks" (only visible under a microscope though) of skin detrius and body oils. That would in principle already be sufficient, but just to be totally on the safe side we also disinfect the roller in Ethanol. If you want to be absolutely sure that your roller is totally sterile like an operating scalpel straight from its packaging in a hospital, then instead of Ethanol, use our Chloramine-T. Chloramine-T kills bacteria like antibiotics do. Chloramine-T has in fact a double antibiotic mechanism of action. And it is cheaper than alcohol as well - from us at least.
Finally, I want to say that we had tens of thousands of customers over the past years and that we never heard of anyone getting an infection - ever. And that's because of what I already explained: "Rolling in" the bacteria on your own skin is in fact quite safe. And simply cleaning the roller well with water and a soapy substance is also sufficient, in practice. That means that disinfecting the skin and roller is actually overkill, and hence nobody ever reported an infection.
Anyone who still is worried about infections should soak the instrument overnight in a Chloramine-T solution and the result is total sterilization.