I have a 5 year old lhasa apso. She is energetic and happy, but keeps throwing up. :( This has been going on for about a week. What could be the problem?

Take her to the vet. We have no idea. Have you switched her dog food? Done anything different? Does she keep water down?

I believe she is keeping water down. We feed her Canidae and we bought a new bag a few weeks ago.

Well I've heard that's one of the best dog foods that you can feed your dog. I wonder if it would have anything to do with the new bag? Is it a different flavor or anything? I would still recommend going to the vet or at least calling and see what he/she suggests.

You maybe feeding her something that might be my she is getting sick you should bring her two the vet

Anytime vomitting lasts for more than a day, you should call your vet. Vomitting can be as simple as a stomach ache or can be a symptom to something quite serious. Be sure to let your vet know if she has been going to the bathroom regularly or not, as well.
BTW, I work in a vet clinic, so I hope this helps!