I masturbate a lot and now I am getting mild penile pain and erectile dysfunction. Why?

Hello doctor,

I am a 27-year-old male. For the past six months I do not do any physical activities, no exercise, I work only on my laptop and drink very less amount of water. I masturbate almost daily for the past 10 years. I never had sex with any girl. I never used any kind of contaminated stuff with my penis. I never had erection problems in my life in fact, I got erection any time I wanted (except when I was extremely stressed). And I always used to have morning erection (until I started research on internet). I usually wear tight briefs, and often while wearing tight briefs when I got erection, the tight fitting underwear tries to restrict the erected penis inside. And due to tight fitting brief my penis bend (where shaft meets the penis head) inside the underwear. And I firmly believe this caused the injury to my penis. When I urinate sometimes some drops of urine are left in my penis head, which comes out later after a minute when I walk back to my room. For the last two months, I have been suffering from very high levels of stress, depression, anxiety, anger related to my job, health, relations, past, and future. And I am severely constipated for the last two months may be due to these stress. I do not have frequent urination.

Last month, I thought I should ask a doctor about this extra skin on my unerected penis (see attached photos). I started research on the internet. At this time I do not have any erectile problems and I was not aware of any kind of terrifying disease that can happen to the penis. Everything was alright. But then, I started reading about the bend I have in my penis (see attached photos) and I read about all these terrifying diseases (Peyronie's disease, prostate, etc.). Since then I am extremely terrified, stressed, depressed, hopeless, more constipated, like someone is holding my stomach tightly. And I also breathe very slowly when I think about these things. I cannot take my mind off these problems. I am terrified like I may have one of these untreatable diseases. After this internet research, I cannot think about porn and stuff which I used to think for erection and masturbation. And even if I watch porn or try to think about porn, all these queries and worries are running into the back of my head all the time and I cannot get erection. Yesterday, I masturbated with a fully erected penis. And I am able to get full length erection (if somehow I draw my attention off these terrifying things).

I am having very mild pain in my penis on erection. It is like a muscular pain inside the penis and had premature ejaculation (this particularly started after internet research). What is the cause of this pain? Are pain and premature ejaculation related? What can be done to solve these problems? I am suffering from erectile dysfunction (problem in maintaining an erection). It does not get hard for more than a few seconds. What is the cause? I noticed a darker patch of skin located on my penis shaft. More specifically it is located on the very bottom of the shaft, starting where the shaft meets the scrotum and traveling up towards the head little ways. It is oval in shape. The color is a bit darker than my usual skin tone. What and why is this black skin on the lower side of my penis shaft? What can be done for this extra skin on my unerected penis (see attached photos)? Is my penis shape normal or not? Why is my penis head bends downward? Is this normal? Why is the head of my penis is large (in length)? And it often remains less hard (spongy) on erection while shaft gets very hard? Why not my penis erection is not parallel to the floor (which it used to be)? It always slopes downward. Is this damaged suspensory penile ligament? Because tight briefs forcefully restricted the erect penis in a downward direction.