threw up blood?

Info before question, I am NOT pregnant, I do suffer from bulimia(they also say anorexia but I am in denial there even though I am at an anorexic weight) I had not eaten yet, but got very nauseated and sick after taking an herbal diet supplement and threw up. It was a little while after I had taken it when I started feeling like I needed to throw up, I did not self induce throwing up, so it was not voluntary.   I threw up bile, and not sure if blood, i know was red(like a darkish red) and I had not been drinking red.  It was first time this morning I had threw up.  I had purged last night but I usually purge handsfree, so  I dont think I had torn anything since I do not use my fingers, it just comes up, and I did not have any burning like ulcer or anything. I felt better after and managed to eat a small meal, made sure it was an amount that I knew I could keep down. Could it have been blood? if so where could it have came from?