Weird belly on on my chihuahua, Help? (PICS)?

Yep, they're right. It's an umbilical hernia. It will probably go away on its own, and even if it doesn't it shouldn't cause any problems. Just ask your vet about it when you take him for his next round of shots. my infant son has one too, and it has closed up nicely on its own. These are VERY common and rarely cause problems.