Thankyou for your reassuring reply.
He is absolutely fine in himself, i rarely see any of my cats drink so am not sure how much he's drinking, but he has more than a healthy appetite - i actually wondered if he is too hungry and whether that is related.
He hasnt had any kitty milk, purely felix kitten. He will scrounge anything else left out so we have to be careful to scrape plates etc.
It is only a small amount of blood and inconsistant so i am not concerned that its anything too serious, but hopefully the vet will be able to shed some light on it.