So last Thursday (July 8), I noticed this on my penis glan

after I pulled back the foreskin, is it from dry masturbation? Sex? I went to the doctor (July 12) and he said that it's an "open wound and that it'll heal eventually in time" I was wondering if anybody else had this happen to them. Also, when it's flacid it seems to close up and be okay but when blood gets a little going it stretches it out (Another Angle

Thanks again everyone! I'm a concerned 19 year old :'). Also it doesn't hurt it just tingles a little after "stretching out"