Welcome to healthcare magic,
It could be herpes
genitalis , which is a sexually transmitted disease
. Grouped fluid filled blebs
which is painful is the typical herpes lesion, which breaks down to form shallow ulcers. It could also be boils
) which is a bacterial infection of hair follicle. I will be able to differentiate the two if you could upload a picture. You may ask me a direct query by clicking on this short url http://bit.ly/dr-j-chacko , where you have an option of uploading a picture of the lesion which will help a great deal in diagnosing the condition.
Hope this helped,