I have white bumps under my pubic hair and I experienced irritation for 2 days what do I have I had unprotected sex now I'm scared

Regardless . Regardless of what i tell you this may be, you need to see a doctor for a definitive diagnosis and treatment. If this happened after shaving then you may be dealing with razor bumps or an allergic reaction. As far as std 's are concerned, it could be crabs. Finally scabies may even present this way. Honestly it is very difficult to say without actually seeing the area in question. Please seek medical care right away.