From what I can see (Being Visually Impaired) is that the blood is in a straight line, a bit like if you were to throw a cup of water across the floor, so if your bunny is like mine and does not like to be held you can check the nails easily, I notice you have a play pen for bunny, so if you go up to the bars and get bunny to come over and offer a nice tasty treat somewhere at the top of the pen so you can look underneath, if the nails are fine then bunny may have sneezed like jersygirl said, if this is the case bunny should see a vet, vets know how to pick up bunnies that don’t like to be handled, it could be and I hope something minor and can be treated with antibiotics, don’t read rubbish on the internet for pet or human heath, we do panic when something happens because we always think it is serious and most of the time it isn’t, a doctor sent me to see a specialist about my knee because I had symptoms of Cancer, all it is is I have Arthritis, all minor ailments and conditions have some of the same symptoms as cancer, but if its not bunnies toenail get her checked, if it is her nose, a bunny cannot breathe through their mouth, so it will be worth getting checked over, our children (Bunnies) cannot tell us if something hurts or bothers them, it might be nothing and then the vet can advise you what to do if it happens again.