So I've had this for like a while. I think it started when I cut myself with a razer.
Then the first time it was this red small bump that exploded and you could feel a sack underneadth the skin kinda. Then it went away forever
then it came back and there was lotsa white pus and you could feel sac under skin
now it's back again but no sac or anything just reddish but does not away
also i cut it once again and i saw white puss come out still.
It's roundish on the skin but more flat this time. It's also very smooth feeling
It sounds exactly like an ingrown hair (which is caused from shaving) Its very common (I get it alot) and the redness and the pus just means its become infected, which most ingrown hairs do. Just apply some disinfectant and it will heal pretty soon.