please don't mess with this, I can't see it so It will be hard to tell. It could be a pimple or infected hair to a swollen lymph node to cancer. I don't want to scare you , Is it on the surface and red or deep and feel like a bead under the skin?call a doctor and until you get in mark it with a permanent marker and see if it gets bigger,,It is important not to out this off,hoprfuly it's nothing but if it were to be a lymph node or a breast lump it will need a biopsy time is important . if it is red and painful it could just be a a number of minor things but still needs checked, Deeper bumps don't mess with it either way time is important, keep track of things until you see the doctor which you should call today .Go in prepared see if you are running a temp, do you sweat at night ?are you loosing weight, Mark the lump ,has it grown? is it painful? Does it come and go or is it always there.. What is your age? do you have any cancer in the family. Do you smoke? I know it sounds scarey but you need have it looked at.Please take care of this.
It sound like a possible abscess, speaking from personal experience. It's mainly composed of pus and dead skin tissue. In time it'll peak, and eventually leak or drain on its own. When it does, drainage and proper cleaning is important. Use oxygen peroxide to cleans the wound and the surrounding areas, and clean dressings (gauze) constantly. After drainage, the swelling will go down fairly quickly, but keep cleaning it. I know that it can be extremely painful, sometimes debilitating. If you can have someone help you with it, the better off you'll be.
And, if this becomes a recurring condition, have it checked by a doctor. There could be a possibility of it being Hidradenitis Suppurativa, which in non-contagious and treatable. Hope this helps, and good luck.
I'd also like to add that many people, including myself, drink 2 tsp of apple cider vinegar daily to help treat it...and, it works. And, since apple cider vinegar is naturally very strong, dilute it in 8 oz. of water, and sweetener/sugar, if needed. Again, good luck.