If it is not a pimple, it may be a herpes outbreak. Polysporin won't help. You will require an anti-viral like zovirax. This will likely get better on its own, but if you notice it worsening, go and get a prescription.
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This is herpes type 1, not genital herpes. I is spread by kissing, and most of the population has it. It may not leak, it may just be a red bump. The other possibility is acne that has not formed a head. Other possibilities are out there, but you're so young that most do not apply to you. If you start having more sores or red spots elsewhere, then I would consider other skin conditions such as rosacea or lupus -- but with one red spot, this would be rather unusual.