What Causes Bleeding Of Blisters Present On The Scrotum?

I am a teen and I am worried, though I am a virgin. I have these blisters on my scrotum and they were bleeding, not a lot, but just some spots. This happened when I was swimming in my pool, but it can't be chemicals, and my friends who were swimming with me, said that they are fine. About four days ago, my scrotum was stinging, so I thought had a rash like today, as it is still hurts little but it was bleeding for the first time. It couldn't be my bathing suit, because I have been wearing the same one past couple years without any issues. So, should I be worried, and what should I do...