My 4 yr old son has been occassionaly passing blood in his urine , on and off for the past week. He also says that it hurts, everytime, he pees and he cringes with pain . Eating/drinking fine and still active with no complaints of pain, except for when he urinates. We ve been to the ER and to see his pediatrican. Both times, they tested his urine and both times it came back negative for an infection . No fever or vomiting/ nausea ....what could this possibly be? Anyone and everyone knows that peeing blood is not a good thing!!!