How To Treat Black Spots On The Shaft Of Penis?

Hi, may I answer your health queries right now ? Please type your query here... i'm 27, 5'9 and weight 151 ..i have small grey/black spots on the shaft of my penis. i've notice i've been itching around my thighs as well could that be cause of concern also? i'm sexually active, and used protect after taking treatment for an std.. syptoms from that std are gone but i'm seeing these grey/black spots n itching now