Serious Penis problems - no erection

I am 19 years old, and I have been having serious penis problems for about 9 months. My penis is noticeably smaller when it is not erect, and the erections that I do get are very weak and need a lot of stimulation to maintain. These erections are shorter, thinner and can be bent. Nothing like what I was getting this time last year. The best way to describe my penis is the way it gets after you spend a day in the pool. Unfortunately it stays that way. It is often cold to the touch now. I went running last night, and when I finished my penis was ice cold. I feel like maybe the blood flow to my penis during both the erect and flaccid states has been cut off somehow.

This situation begin when I was masturbating a while back. While I was doing it I heard a "pop" sound and my erection went into this state and has not recovered. There was no pain though. It would mean a lot if you could give me some feedback, because I can find nothing similar to my situation online and have been effected very negatively by the situation. If you have any questions please ask.