Im 34 I had a colonoscopy about four years ago it came back that I had a non-cancerous polyp, other then that it was good, but recently I've been noticing my butthole is very itchy and whenever I have diarrhea or constipation my butthole hurts almost like a splinter or a piece of glass is coming out then when I wipe there's either very dark blood or very bright red blood and now I feel like my butthole is swollen or it has something hard inside, it's very tender. I use Vaseline to relieve the pain because it's very sore afterwards. Any idea as to what it can be? I won't be able to see my gastro Dr until May and I need some relief 
Also, hemorrhoids, colitis and colon cancer run in my family my grandmother had colon cancer at 45. I drink plenty of water and have a prescribed fiber powder mix that I drink three times a day.
Best to make appointment with your gastroenterologist. Probably hemmoroids or maybe a fissure. Good luck.
Red blood comes from more from close to entrance, black blood comes from higher up inside, you need to get this checked out, could be hemorrhoids the red, but the black blood could be from digestive track hope this is some help.