What to do about toddler vomiting once or twice a week?

My daughter is 2 and she's been going through these weird spells where she will vomit once or twice a week and its usually at night. I know when something is wrong when she doesn't want to eat most of the day and she even tells me her tummy hurts. I went to the doctor a month or so ago and they gave her Singular to help with the nasal drip (could be causing bad reflux). She does have a hernia, but the doctors have said that its no big deal right now. But I'm wondering if this is the cause of these spells. Please help!