Any advise on someone who's 38 weeks pregnant and can't keep down a full meal? Almost everyday if I…

Any advise on someone who's 38 weeks pregnant and can't keep down a full meal? Almost everyday if I try to eat a full lunch I'll throw up or even before I start eating I'll have diarrhea immediately after having the thought of food. I'm just worried because I've lost 3 pounds and my doctor got really concerned about it. I'll still eat healthy snacks like fruits or protein breakfast bars and stuff. I just feel like I'm not eating enough for my baby. :/