Yes L Have Gerd But Feeling Really Sick When L

yes l have gerd but feeling really sick when l eat the foods that l was told it's okay to eat,,how to l know if l have another condition like IBS or allergic to gluten ,,,l am sick when eating lots of different food and lost 15 pounds ,,,,even shredded wheat cereal with soy milk make me sick,,l dont know what to do,,how do l get a proper diagnosis and help
my doctor referred me to UCSF in the mean time don't know what to do