17 weeks pregnant with eating problems..please help!?

Im 17 wks preg.& have been having some trouble eating when i consult the dr Im told that the baby will get its nutrition no matter what but im really concerned for both me and the baby, this morning i ate 1/2 a burrito and then i almost threw that up and when i tried to eat something else later i thre it up and havent been able to keep anythign else down, and yesterday i ate a healthy 1/2 of a turkey sandwich and then it came up and then i tried home made nacho's and cheese and that to came up too. i cant take my vitamins becausde i throw them up no matter what so i try to drink vitamin drinks which i can barely keep down. my stomach has been contracting ALOT but the dr's say its normal and they dont even check it out. i have ped out 4 times in this pregnancy and when it happens my ears begin to ring and then i cant hear anything then boom im out and when i asked the dr's about it they say nothings wrong and i think it has to do w/sugar because if i get sugar afterwards i feel fine.