Sounds like a case of UC, [Ulcerative Colitis], But try and stay calm because stress can aggravate any health problem .
The two things you didn't mention that happend with me when I had it was Mucus also with the blood, and having to have stools frequently that were loose.
Now that doesn't mean you have UC, just brought back memories from the 60's when I had UC. I too was okay in every aspect but this. I went to an proctologist who tried various drips of meds in the hospital for a few days, but nothing helped. Then he told me that He would have to do surgery. Cut my colon, and place a bag out side my body to deficate in.
That was the end of seeing this guy. I told him I would rather die from the UC rather than what he was suggesting. So I started reading about it, and found out the bowels were causing this because I was eating something that didn't agree with me, and probably to much of it.
So I reasoned that if I fasted I should get rid of the problem. It did after a 10 day distilled water fast I no longer had the problem. Eventually I returned to my old eating habits and the UC returned. Not right away, but a few years. So I fasted again for 10 days and the UC was gone again.
Like I said this was in the 60's. I was smoking a lot of pot, and with that comes a lot of munchies. Most of these munchies are loaded with sugar. I backed off the sugar, and I haven't had any more UC.
Wasn't easy, but it beats dying, or a bag.