What Causes Urinary Canal Blockage?

It feels as if something is stuck in my urinary canal. I am a male, 20 years old and it just feels like i have to pee all the time but it comes out in very little streams. I urinate a bit more normally when i drink lots of water throughout the day but the feeling is still there. My urethra looks as if it is swollen and can be constricted than normal. I am constipated if that also helps. Can this be a UTI? Herpes? Stricture? Kidney infection? I know it will be hard to diagnose but just looking to get opinions. I went to get an STD check today but a herpes test was not initiated because i don't have signs of anything like that...yet. I also drink a lot of alcohol and smoke a lot of cigarettes and smoke a lot of weed.