Dermatology Questions? Ask an Online Dermatologist.
Thank you for your question. My name is***** and I will do my best to provide a useful input.
Would a photograph of the affected area be possible at your convenience?
Apologies did not get an alert that you had responded. Okay so bumps that disappear this quickly are just normally due to skin irritation from any reason (heat, friction, synthetic undergarments etc.) - in your case they were very likely caused due to the old/dull razor. I don't see any evidence of an STD in your history or clinical picture. Nothing to worry about and now that the problem has cleared no treatment is required.
Please feel free to ask if you have any queries. I will be happy to continue further and do everything I can to provide you with the service you seek.
Also probably skin irritation - a canker sore is very painful and lasts 7-10 days, same thing with a herpes sore.