Cluster of white bumps on ...reasons?

I have a cluster of white bumps that came up about 2 days ago. This has occurred about 2 times before, but always I've applied some hydrocortisone and their gone overnight. But this time they have stayed present for 3 days...Im concerned. I just had a full STD exam done and received the results and Im NEGATIVe for HIV, NEGATIVE for any type of RNA virus (meaning no or anything). Got my results just last week and have only been intimately involved with one guy for 3 years.These just popped up on Wednesday after me scratching an itch. It seems as though they always come after scratching an itch on the surface of my , but usually they are gone by now. My concern is with the fact that they have been around for so long. I believe it could be a bad rash... do u agree or what are your thoughts on the issue?