What Causes Pimple Like Bumps On The Hood Of My Clitoris?

I have small pimple like bumps on the hood of my clitoris. I ve been tested for stds no less then a month ago and My results came back negative ...I am on my menstrual but I m not suppose to be because I have pcos and my blood count was low...so they stopped it for now... Since I came on I been irritated a little & itching ! What could be wrong