trying to treat my sick dog?

Hi guys

I have a four year old female chihuahua (about 7 lbs) who has been sick for about two weeks now. She has been sort of tired and been sleeping a lot lately, bloated, and she had visible stomach pain, just two days ago she threw up, we tried keeping her hydrated, and keeping her off of food for a while and decided to wait through the night.

That night she threw up again, about every 15 or so minutes or so for several hours, at first bile (yellow and frothy) since she had no food in her stomach, and then with blood. Later in the morning she had pretty bad diarrhea, also with blood.

We were going to take her to the vet if she did not feel better in the next couple of hours. We kept her hydrated, and she ate several hours later and seemed much better. We always keep her on a very strict and bland diet, home-cooked boneless, skinless chicken with rice and carrots, and dry hills science puppy bites at night. Since yesterday she has only thrown up one more time, and she is much more active, however still bloated.

To keep her from having too much bile-build up in her stomach we are gonna try to feed her multiple times a day instead of just 2 a day, and we were also considering adding Prozyme to her food (let me know if you know anything about it).

The problem is that throughout her life she goes through a cycle every two months, for a couple weeks she is very healthy, and then she gets sick (not as severe), she has diarrhea, doesn't pee much, and vomits. And then she becomes healthy again, and we don't know what is wrong.

She has only been severely sick one other time in her life, and we took her to an emergency vet, they gave her fluids, and sent us home, they said she might have pancreas problems but they don't know, any suggestions?

Thank-you!