I think I may have damaged penis severely

Today, about two hours ago, I was in the restroom masturbating normally. I have been masturbating for many years now, but this morning I tried something I now deeply regret.
I read somewhere that stretching the penis shaft can lengthen the penis, so I tried it. I stretched it in the morning, while sitting on the toilet, downward and side-to-side. Everything was normal after the stretching session, just a slight pain similar to that of stretching your thighs.
Well, anyway, I masturbated as I was taking a shower, and immediately afterward my penis decreased in length. It literally shrunk about half the size when flaccid regularly. I thought maybe  it was the cold water, but when I got out of the shower, my penis still looked very small. Then, I tried playing with it, and I noticed I had lost much sensation in my penis, and it would not get erect. I tried to get an erection by watching porn but it didn't help much; I'm very worried that I may have damaged nerves permanently and that I will never get my full erection like I used to. Does anyone know if it will get better in a certain amount of time? I'm planning to go to the doctor's tomorrow. Also, I think I may have damaged the corpus spongiosum or something like that, because when I lifted my penis to check the underside, my scrotum would rise with it, and my testicles seem much higher to my penis, or maybe the shortness makes it seem so. I'm seriously very worried and would very much appreciate anyone's input. Thank you.