Welcome to Just Answer.
How large is the sore?
Please enter reply.
Where in the foreskin exactly?
After how many hours did it develop?
Did you feel pain during sex?
It is likely to be due to a trauma.
STD would not come up in a few hours.
It takes sometime to develop.
When you had pain during sex, there can be a trauma.
But when it is an inch long, you should get an examination by doctor.
You can apply neosporin antibacterial cream.
But it can get infected from contamination.
Doctor can check it & prescribe medicine to prevent it.
Yes, the area can appear whiter.
It is likely to be from trauma.
Please do not worry much.
You are always welcome.