Im so sorry to hear about this recent update! It seemed like he was doing so well and was really going to come through this without major problems.
Has your vet talked about doing an ultrasound to look at the spleen and liver (the most common organs involved with internal bleeding)?
Just remember that this new drug Can be hard on the liver. Doesnt mean that he will have problems with it. I hope it does the trick and helps Sport with no side effects! HUGS!!!!!