Does anyone have any experience with horse nose bleeds?

Ut oh... The last nosebleed that wasn't caused by an injury I was around was caused by a horse trying to p a "stone" and with your dad's horse having on and died from it I'd have a tendency to think that the two nosebleeds are related. Is your water mineralized? If so, your horse could have injested a small pebble while feeding and the water would have added a LOT of calification to it, thereby creating a "stone" and your horse is now trying to p it and that's what's causing the nosebleed. Call your vet, play this senario by him and see if that's the case.