Hi purple9812,
Was the blood a bright red or dark like black coffee? I had a kidney stone 20 years ago and pee looked like coffee. Had it a couple more times and it went away. But then I got the PAIN. Kidney stones hurt like hell. I was sitting in the kidney stone center and two ladies were talking in front of me and one said to the the other " i have had 2 kids naturally that did not hurt as bad as this kidney stone" scared the hell out of me. I literally drink at least a gallon of water EVERY day. never had another one (knock on wood).
Dark blood usually means it is up in the kidney and a brighter blood means that it's probably working it's way down the "tube" or in your bladder. You probably passed a stone! congrats. They are jagged and sharp little bastards.
Blood was not from anxiety but it will give you anxiety until your reassured it's nothing serious.