If you have hard feces it will tear your sphincter on the way out. Because it is bright red I would guess you have a hemmroid. If it continues for more than a week I would see your doctor.Put some bacitracin on your rear to ease the discomfort.
Eat more fiber. It might be hemorrhoids. It happens when u lift heavy things. Eating fiber will make sure your colon is clear and you don't have very large dinosaur sized poop. It should be soft. If not eat more whole grains,fruits,and veggies.