My newest kitten displayed the same symptoms when I brought him home, along with some nasty diarrhea. I took him to the vet right away and it turned out to be an upper respiratory infection. They put him on antibiotics, deworming stuff, anti-diarrhea meds, and fortiflora to help with the runs as well.
You should definitely take him to the vet as soon as possible because with young kittens if not treated it can get bad pretty quickly, mine did end up having to stay overnight for a few days. Also, as the others above stated do not get him vaccinated until he is well and healthy as the vaccinations lower their immune systems and he needs that right now. I'm pretty sure any decent vet would tell you that though.
Good luck with the baby and keep us posted!