Bleeding from the Anus
This one can be hugely serious. The need for urgency depends on the volume of blood. Probably, if you are reading this, your bleeding is not a large volume, and you are concerned instead of worried. You may still be scared, though. So let's deal with the urgent stuff straight away.
If the blood is bright red [arterial blood], or "clean" and dark red [venous blood], and comes in what you feel to be a worrying quantity, major blood loss may be involved. Stop reading this and call the emergency services now. Better to look and feel an idiot later if you were wrong, than to be dead.
Still reading? Ok, then the blood loss must be relatively trivial, and you're either simply worried, or embarrassed. There is still one major area to be worried about. Have you or your partner inserted anything sharp into your anus? Piercing the bowel wall isn't painful at the time of injury, but it will allow bowel bacteria into the abdomen. There is a major danger of massive infection, peritonitis, so swallow your embarrassment, and call your doctor. Now!
Other bleeding is likely to come from an anal fissure (tear) caused by either insertion of too large an object or insertion too fast or without sufficient lubricant. These sting. They sting like hell. They need to be kept clean, and treated with a simple germicidal ointment (ointment is oily, so use it instead of cream, which is often water based). It helps if the faeces are not rock solid, so eat plenty of fibre in your diet. Don't use laxatives. Avoid spicy foods. If faeces are hard, consider an enema to loosen things up simply and easily. Refrain from anal sex until several days after the day you are "sure it will be ok". Opening the same fissure over and over again will lead to scar tissue, and this will eventually make dilation of the anus very difficult. Ignoring the pleasures of anal sex, which will become impossible, passing faeces becomes difficult and surgical intervention is then needed.
Darker, clotted blood may come from piles, haemorrhoids. Varicose veins inside the rectum. Sorry to give you this news: repeated bouts of piles often mean the surgeon, or at least a surgeon's opinion. Forget "Preparation H", just swallow your pride and let the gastro-enterologist enjoy looking up your arse! You've only got one, so take care of it.
This area is vital to keep healthy. There is too much potential for infection to delay. If in any doubt, go and see your doctor. Do it today.
One thing, though. A tiny smear of blood on toilet paper, just a smear, is nothing to worry about if it is a rare thing. More than that? Find out what is causing it. And if you are worried, even the smallest worry, take your anus to the doctor.