Weird lump/ bump thing on my chin?!

Soo i have this weird bump/lump looking thing directly on my chin. Its like a swollen spot its all reddish and when i touch it i just feel a big round lump its hard. What is this? I mean i have acne around my chin area too but this definitly is not a pimple. I noticed it actually comes and goes too its very odd. I noticed it like a week ago but then i didnt see it again till today. What is this?