I Have Red Spots On My Penis. I Noticed Them

I have red spots on my penis. I noticed them almost 2 weeks ago after mastrubation. I never had untpotrcted sex but i had unprotected oral once. I even kissed her but my mouth is allright. I had std test done and its all negative. Couple of days before i mastrubated again to see how it reacts and then one of the bumps started paining when touched and i couls see some black swelling underneath the bump. On the second day, i found other bump on the place where i put pressure while mastrubationg and it even pains when touched. No other bump causes pain or irritation. My penis even started paining sometimes after that. Can ypu please tell me what it is?