Thanks for your response. The other medication the vet put him on we don't know because she had to hand the tablets back in this morning sorry.
My Mum took him back to the vet about an hour ago and has now referred him to the emergency vet in Leeds. She has just rung me from there and he has been admitted. They are starting all the tests again today and giving him a blood transfusion later on tonight. He is in the best place now, they are really good, have all the equipment inc scanners etc. She has just rung me again to tell me there is a slight heart murmur and a cardiologist is going to look at him later as well.