Pain and bleeding after ejaculation, followed by urinary difficulties

I am a 21 year old male in generally good health in a sexually active, completely monogamous relationship.
Six days ago, I masturbated in a sitting position and experienced a series of very sharp pains within the penis at the base of the shaft (inside the urethra). I had not ejaculated for about ten days before this, and had just finished an eight hour car ride the day before.
The pain, a pinching, burning type pain, continued throughout the hind parts of the urethra and any pressure put upon the perineum caused additional pinching pain in the urethra. After about an hour, the pain started to slowly subside, and I went on a walk. During the walk, the pain essentially disappeared, but when I returned and attempted to urinate, I discovered that I had been, and was still, bleeding from my urethra. I eventually bled enough that the spot on my boxers was several inches in diameter; this was NOT just several drops.
(NOTE: this was not blood in urine, or blood in the semen, this was, from what I could tell, pure blood. Seminal fluid may have been mixed in, given that I had previously ejaculated, but the mixture was definitely frank blood)

I promptly went to the emergency room, as the amount of blood was relatively large, and I had never experienced anything like this before.
After examination, the doctor there thought I may had somehow ripped the lining of my urethra or had some non-bacterial urethritis. I submitted a urine sample, which did not show any signs of infection. I was prescribed a week's worth of 100 mg doxycycline just in case, and to combat any secondary infection.
Later that evening, the bleeding seemed to mostly stop. I started experiencing sharp pain on the ventral, posterior end of the urethra at the base of the penile shaft upon urination. I also had intermittent pains within the penis without urination, but these eventually got better.
Over the next few days, I drank plenty of fluids, and some of the pain during urination subsided. I did notice some definite decrease in urine flow/pressure, as well as starting hesitancy.

Now, almost a week later, I'm still experiencing strange symptoms. I have abstained from ejaculation for fear of tearing/rupturing whatever may have come undone before.
I have some mild pinching pain still when I urinate, some urinary hesitancy, and when I urinate, it seems like I can't fully empty my bladder. After urination, I feel like I don't need to urinate any more, but the amount I end up urinate doesn't match up well with the level of urgency I had before urinating. I also have occasional pain and pressure in the perineum area and lower abdomen. My urethra generally feels "off", and the pain where I have the most pain during urination feels somewhat tight or congested (I know that's a sensation that doesn't translate well into words; it's like I feel blocked). A few small drops of urine, after urination, seem to get caught somewhere in the urethra, and have to "kick" them out with muscle contractions and gentle massaging.
As of today, I noticed after urination, I've been getting a small amount of a clear, sticky fluid that is left behind on the opening of the urethra. I haven't noticed any discharge without urination. The fluid resembles seminal fluid or pre-***/post-***.

Is is possible that I somehow developed a urethral stricture overnight? I had very little urinary troubles before the pain during ejaculation, and the masturbation was by no means overzealous.
Could I have popped a blood vessel in the prostate or urethra, or are these symptoms consistent with the doctor's diagnosis of tear in the urethra? I don't think I actually fractured the penis, since the masturbation wasn't rough, there was no "popping" noise, and from what I heard, it's a pretty obvious thing and can't be mistaken for much else. Or is prostatitis to blame? The passage of a sharp prostate stone?
Since it's likely I don't have a UTI, or any STIs, I'm worried about having a traumatic injury or physical issue that requires surgery. I'm confused on how this could be, because as far as I know, urethral strictures are either congenital or take a long time to develop (and my symptoms started with one, sudden event)...and traumatic injuries, I would imagine, would take more force than run-of-the-mill masturbation to occur.

I'm going to make an appointment with my doc and possibly get referred to a urologist.
Any advice, suggestions, and help would be very much appreciated. I am very worried about my symptoms.