Nausea and eating

My wife is having major nausea. She's about six weeks along and has gotten two different medications from the doctor to help, but it doesnt seem to help. She isn't eating because she throws up everything she eats shortly thereafter, but she also says the nausea isn't as bad if she's eaten something. I keep telling her she needs to eat. She's losing instead of gaining weight. Any suggestions of what to do?