Dark spots on the penis' glans?

I don't know if this matters but I'm 19 and uncut. I was masturbating and after I was done I looked at my penis' glans and noticed purple spots on it. I was concerned but thought maybe they'd go away so I went to take a shower and while in the shower I pulled back my foreskin and see that it's now black spots on the glans! I'm kind of having a panic attack because this is scaring me, I've never had this problem. I'm just scared now that it's something serious and the dark spots won't go away. I searched online and ran across the term Balanitis. Apparently it's inflammation but I'm wondering if anyone who's had this did it go away? If so, how long did it take? I'm sorry if some of this doesn't make sense but I'm freaking out and typing as fast as I can!