Something is wrong with my chihuahua! Help!?

Have you examined it closer to see what it may actually be? My cat did this once. When I took a closer look I saw something black and saw that it was one of my daughters hair ties! Apparantely she had swallowd it and was having trouble passing it all the way. I pulled on it and it came out. She complained a little but was fine immediately after. I would say you should take a closer look and if it looks like its part of her don't pull it and bring her to a vet. If its a foreign object try to gently pull it out. Also she might be able to pass it on her own. If the problem gets worse bring her to a vet.