Why is my dog bringing up bile?

My ( nearly ) eight-year-old terrier bitch keeps having recurring issues of bringing up bile and sometimes a diarrhoea like type sick. This seemed to begin after we returned from a holiday in June where Missy was quite unsettled and didn't eat for almost an entire week until the day before we left, she also had a bad bout of diarrhoea during our stay too.
At home she started eating again and that's when the sickness began. I know bile is normal and normally indicates an empty stomach and as she was throwing up over night I assumed she was hungry. So after advice from some other dog people on a forum I belong to I started giving her a night time treat to tide her over to breakfast and started adding a bit of natural live yoghurt to her diet. This had varied results but it seemed to help improve with her sickness. And then about a month or two ago she stopped altogether and we had a few good weeks with no sickness until, that is, she started bringing the bile and sick up again over night these past couple of weeks or so. This week alone it's been every night since Sunday with sometimes up to three lots of sick.
Missy is fed a good natural food once a day in the evenings with Applaws tins of meat mixed in as she will barely touch her dry food. She never eats breakfast and after years of trying to feed her two set meals each day I went with what she seems happy with. She does get treats during the day and late evening so I don't think it's hunger. She is perfectly fine in herself and is why I've perhaps been hesitant to take her to the vets, after being told (and knowing myself) that bile is normal and no change in Missy's behaviour.
I'm not sure if this is something to be concerned about or not. Although, one behaviour change in her is that she is almost obsessed with eating grass at times and occasionally along with the bile she has also sicked up pure grass too.
Any advice at all would be greatly appreciated.
Louise Nichol by email

Bilious vomiting first thing in the morning is a common complaint, and one where I would agree with the advice you were given, ie feeding a small meal at bed-time to give the stomach something to digest overnight. As you found initially, that is usually enough to settle the problem. When I was competing in dog obedience, a good friend had a beardie who simply had to have a plain biscuit before going to bed, and then a small meal as soon as she awoke in the morning, in order to avoid yellow vomits.
I am therefore concerned, like you, that the bilious vomiting has started again. Another possibility is that it could be a nervous reaction. It is interesting it began whilst she was on holiday when, you say, she was unsettled so I wonder whether there has been any change at home to set this off again. It could be something obvious like visitors or having the builders in, or a more subtle change such as a new suite of furniture or a change in your daily routine.
Otherwise, I do think an examination by your vet would be worth organising. There may well be an underlying problem which therefore should be diagnosed as soon as possible so that appropriate treatment can be given. It cannot be pleasant for your dog to be bringing up bile so the sooner a cause can be found and treated, the better. Eight-years-old is not very old for a terrier, but old enough to be wanting to rule out serious problems.
Alison Logan, Vet