[lolabella]

Mia is 9-10 weeks old, and we got her last Saturday. She had been doing very well until yesterday when she vomited in her carrier. She had had a lot of excitement though. First she went to the vet's office for her first visit, then we took her to the mall to get her carrier, and there she met lots of people (which she loved) and she also got many treats. Even though she vomited, (and had to be washed) she was happy and perky after she took a nap. Well, today she has not been eating well. I gave her a couple of pieces of her dry food by hand, but she lost interest after a while. She drank little water, and she has been sleeping all day. She always tries to follow me inside the house, but today she just hides behind our "groove bag" (which is a bean bag on steroids). She lifts her head when I say "Mia" but then puts her head back down. I called the vet about Mia's disinterestedness about food and I think the vet receptionist thinks I have nothing better to do (and I don't think she is familiar with the needs of Yorkies) and she just told me to look in the back of her food bag for the necessary amount she needs to eat every day and maybe give her some canned food (that i mentioned she usually likes). Mia got more sleepy after I called the vet so we gave her a tiny bit of nutri-cal in case she has low blood sugar but she just went right back to sleep.
My question is, should I continue to freak out and take her to the vet? Is there anything to watch out for? Please help, I don't know if she is sleeping because she is a baby, or if there is something wrong with her.