I get blackheads very often on my chest. A few months ago, a stubborn blackhead on my chest became infected and a ton of pus 
filled up the spot. After a few weeks, all the pus cleared and the area looked better. I think its healed since then, but now I have a reddish brown bump from where the blackhead was and I have no idea how to get rid of it. I don't know if there's still anything inside or not. It's really affecting my confidence when I wear tank tops/bikinis! What can I do? (sorry for the gross pic)
Hard to say what this is, ... may still have infection in it. Please goto a dermatologist and have it treated. Redness is normal after wounding. IT's called PIE. He may inject it, extract it, or use a steroid.
You can try castor oil and or comfrey on it to begin with. Also retin a /tretinorin / differin is effective. These areas can take up to a year to heal. If not responsive you need vascular laser to address pigmentation.