Try this:
B complex liquid- put the drops under the tounge 2 x a day.(follow bottle). B6 deficiency can cause the nausea and b3/b5 can cause the vomiting. Taking a b complex liquid is best- because these viamins rely on each other for uptake. For example b3 needs b2 to convert it. Excess b flushes out if I remember correctly.
Magnesium- prenatal vitamins are usually low in this mineral. The National Research Counsel recommends a minimum of 450 mg during pregnancy. I think that is low, I have read that 8 mgs per kilo of body weight were required, or 560 mgm for 155 lb adult (not pregnant). keep in mind that you might take in somewhat adequate ammounts from foods and still become deficient because, 1. cooking destroys it, 2.processing and pasturizing food destroys it, 3.phytic acid found in cereals binds it, 4. high carb diets deplete it, 5.malabsorption from vomiting or diahrrea depletes it, 6. stress, trauma, and pregnancy depletes it, 7. sugar and colas deplete it, 8. taking calcium,zinc or iron supplements without adding magnesium creates deficiency, (drinking to much dairy causes over-calcium/under magnesium issues because milk is 9 parts calcium to 1 part magnesium) 9. Antibiotics and a host of other prescriptions depletes it, 10. Exposure to florides and chlorine in water depletes it, 11. Soy in all forms and kinds reduces circulating magnesium in the blood. (Only 1% of our magnesium circulates in the blood as it is.) It is because of the estrogen affects of soy that this is so. So any other 'estrogenic' food or chemicals (like America's main fertilizer on crops) will deplete magnesium from the blood as well. Therefore high estrogen during pregnancy may be a reason some women get sickness and vomiting. Magnesium deficiency can cause nausea and vomiting symtoms.
Options are Magnesium malate pills,or the best is magnesium chloride. "nature calm" magnesium powder for drinking, or magnesium oil (magnesium chloride hexahydrate in water suspension)sprayed directly on the skin and let dry. Do one or two of these magnesiums options daily.Excess magnesium flushes out. No worries. If you get diahrrea cut back the dose a little.
Also you can try putting lemon on your water.
I would not turn to prescriptions like Zofran.It has lots of side effects, side effects that show it affects the central nervous system. Some of the side effects, like hiccups, tremors, numbness,and slow colonic transfer seem to show that it affects the magnesium levels of the body as well. You cannot afford to affect your magnesium stores when you are pregnant. They are VERY important to maintain, and they are hard enough to maintain an adequate level as it is. Studies show that women with depleted magnesium are prone to preeclampsia,high blood presure, gestational diabetes, and miscarriage.
Of course you should do your own research on these topics or consult a licenced MD.
Blessings, Gail