I'm not sure what it means to have "white stuff under my penis". If this is on the skin between the penis and scrotum, it could be a fungal infection or just tissue maceration (irritation, skin softening), especially if you are overweight. It doesn't sound like any STD, and you clearly aren't at risk for STD. You should see a health care provider. However, it probably wouldn't hurt to try one of the OTC antifungal creams you'll find i the pharmacy, ie something for jock itch; plus frequent washing (2-3 times per day), plus drying agents (like talcum powder) in your underwear. But definitely see a health care provider if these things don't help within a few days.
Good luck-- HHH, MD
I am no doctor but I think an antifungal cream or a hydrocortizone cream should be attempted first to see if it improves matters.
I was diagnosed with herpes following symptoms similar to yourself but the so called expert dermatologist got it wrong.He never conducted any tests.He just said that it was herpes and prescribed Zovirak tablets.
My advice is that if the antifungal cream or other creams don't work , get to an STD clinic and get checked out for peace of mind.
If I were a betting man, I would say that you have balanitis/eczema and NOT herpes.
Your symptoms are describing what I went through for years.
By the way, I never got sorted satisfactorily and had to have a circumcision 6 months ago to fix it permanently.