i have bruised my tailbone, it took months to heal and couldnt do anything about it.
I also once had the occasion (on multiple times actually) to have blood in my stool, i wasnt using my butt for anything but sitting and shitting. I was too weird about mentioning it to anyone at first and thought maybe i was just trying to hard while constipated . I eventually told someone about it and read up on it and it can be a myriad of horrible things and that scared me into going to the doctor. it turns out i just internal hemmoroids (sp lol) from a poor diet. More fiber fixed me right up, hopefullly its a similar case for you