Was given a shot of Lovenox back in 2001 and it caused something to burst in my small intestines. Luckily I was already in the hospital, started pooping blood by the pints and they done an emergency colonoscopy while I was awake.
About 1 minute into it I passed out.
When I woke up in ICU they had already put several pints back into me and said I was still 2 pints low but my body would make up for it. Was in there for a week, that sucked.
A year later another one bursted and they never found it either, I have veins growing inside of my intestines, forget the name they called it, but they burst every now and then.