I am going through the exact same thing right now with my 13 year old black lab. I have had him to 2 vets. His blood work is ok but I have not had xrays because he is older and hates to go in the car.The last time we took him he got excited and bleed everywhere. He seems to sneeze a lot when he gets excited and that is when he bleeds.
We were preparing to put him down when the last vet came to the house because he wasn't eating or sleeping. We put him on a pain medication for 5 days and have him on anitboitics for 14 days(5 days left). He has since been sleeping and eating again and seems vey happy for an old fellow. There is no bleeding accept when he gets excited.
We are using rescue remedy to keep him calm which works ok. Alergy season is bad right now adn I hpefully that maybe alergies could be a cause. The vet is coming again in a few days to check him out again.
I have been told that his heart maybe weak with possible clogged arteries. I have not been able to come to an exact reason as to why, more then likely it is cancer but I am hopefully it's not.
Anyone have any input that would be great. Please keep me advised as to what you find out and I will do the same .
Water and Wishbone.