Hi, thanks for using Petco Pet Education Center, formerly Petcoach! Awww, Romeo is adorable!
Parvo vaccinations should be started at 7-8 weeks of age, so at 5 months Romeo is more than ready and is at risk for the virus. At 5 months he will only get 2 DHPP (Distemper, Hepatitis, Parvo and Parainfluenza) vaccines 3-4 weeks apart. He is also old enough for his Rabies vaccine. He may be thin from intestinal parasites. Bring a stool sample with you to your first Vet appointment and expect that he will be dewormed as well. Romeo should also start heart worm and flea/tick prevention.
I hope this helps and I wish you and Romeo all the ebst!