I am a 19 year old guy and have very clear skin, but for the last 1 or 2 years I have had these weird lumps on my chin. they are tiny, about the size of a pin head, although some are bigger. when i squeeze them sometimes something like sebum comes out, but a lot of the time they just become inflamed and for that reason i no longer do squeeze them. What are they? how can I get rid of them? salicylic acid? retin a? other? please help!