My 8 year old son has vomited three times today. No fever, no pain. The first time we assumed he ate too much breakfast. The other 2 times, we thought were maybe car sickness. However, the third time there was blood in his vomit. Not just redish colored spit, it was blood. He fell asleep after that, and slept until we got home (about 25 min.) he is now fine. Still no fever, he says hes not in pain, and he is acting fine. Should we go to the ER? What may have caused this??