A nurse drew blood from both arms, then took blood pressure..?

[sonicsr64]

I went to the dr. yesterday and I had blood taken from both arms. Not really a big deal, but then she took my blood pressure and the area where the blood was drawn started bleeding again, and formed a knot. She applied pressure and an ice pack and said that it was nothing to worry about. well now, approx. 24 hours later, the bruise is really big, the knot and pain have almost gone away. But now, I have blood in my stool. I was wondering if that was a side effect from what happened with the blood pressure incident or if maybe it was a side effect from my new medication (started that last night). I don't feel sick or feverish or like anything is wrong, just blood in my stool. Any help with this would be greatly appreciated!