Male Yeast Infection or an STD?

Hello.

I am a 20 year old male who has had unprotected sex with the same partner for the past three months. My gf (partner) has been diagnosed with HPV and has no other STD's. I assume I have HPV as well but was told I would not experience any symptoms. Unfortunately, two months after we first had unprotected sex, my scrotum felt extreme discomfort and turned red in areas at the base of the penis. There are a few red bumps very very small around the red area but do not hold "fluid", "wart like appearance" or "burst into bilsters". I also do not have any fluid discharge or burning while urinating. My scrotum burns and itches constantly. It feels very tingly and if I touch the red area it will spread all over my scrotum. The red area is very moist and sticky almost similar to jock itch. The weird thing I can't figure out is that it only lasts for a few days then it's gone. After a couple weeks I get it again. My gf and I just had sex four days ago and she complained for the next two days she had extreme urination pain maybe a possible UTI. At that same time I had a flare up of this inflammation/rash. I am too scared to confront her about this matter or go to a doctor. Too embarrassed and ashamed of my situation. The more I read I'm terrified I might have genital herpes but the redness is only in my scrotum!!! Could it be a yeast infection? From what I have read a male yeast infection affects the head and tip of the penis. I am not experiencing any of those symptoms. This is horrible. Any feedback I would GREATLY appreciate it.

Thanks