My 4 month old kitten sneezed a little blood- is this normal with a URI?

I just adopted a 4 month old kitten from a shelter, five days ago I took him to the vet because was sneezing, he has a kitty cold (uri) and is on clavamox, he seemes to be getting better, no watery eyes, huge appetite, drinks water, plays, oh adn no more fever...buuuttt he is still a little congested and has sneezing fits here and there....tonight he sneezed and there was a tiny bit of blood. Is this from too much sneezing? Dry nose? And do just have to let the cold run its course like us humans do? I dont want to bring him back to the vet if I dont need to...i just need peace of mind! Please help!