Had unprotected sex with my girlfriend and my penis got swelled up and a day later i got a white painful pump on my penis . why is this happening ?

See below: Difficult to know without being able to examine but suggests some possible overuse.Trauma-related inflammation or even allergic-type reaction if any lubricants used.. Any std (e.g. Herpes, syphilis, genital warts) would take significantly longer than 24-48 hours to appear. Would expect improvement or resolution within 24-48 hours if not significant.