I suggest seeing your doctor!! If the blood in your stool is dark then it could be internal bleeding. If it's bright red and on the tissue paper then it could be an anal fissure. See your doctor!!
Any time you have blood in stools you need to be checked by a dr. After a trauma you need to be careful of internal bleeding. I say go to the ER right away!
Agree with the above. When ever you have trauma (an injury) to the abdomen, you run the risk of having internal bleeding. This can present itself in several ways, and one of them is blood in the stools. Another is being nauseous (or as you refer to as heartburn and feeling sick). There are many organs inside of the abdomen that could have been damaged when you were assaulted and you need to be worked up to see the extent of the damage.
You need to go to the ER now to get checked! Your doctor will not be able or have the equipment to do this type of work up. Do not hesitate in going.
Go back to your doctor ASAP, these symptoms point to internal bleeding, this is not good. If you can not get in soon, then head to the ER.