Why does a 5-month-old baby not eat and vomit if she eats?

Hello doctor,

My daughter is 5 months old. She vomits up everything she eats. She did not eat anything from mid-morning. We tried giving her some baby oatmeal and she would not even eat at all. We gave her that in the evening after trying her usual 6 oz bottle that she did not take even an ounce of it. She went to sleep at 11 last night and did not get up today until afternoon even after I tried waking her all morning. Her soft spot seems fine. This has been going on for about a week now. I took her to the doctor and they told me all was well. If all was well, why she is not eating? She has no fever. No weight loss. She also has not been urinating as often as she should. I only have to change her once or twice a day. She does not seem dehydrated. She has completely white eyes. She jerks her arms and legs pretty hard as if she is having a seizure? Or the infantile thing? She does not cry when it happens or anything though. I am concerned for her but where I live it seems no one knows what is or might be wrong with her. I am not getting any help. She is just little and cannot tell me what is wrong. I do not know what to do. I have been to more than one doctor in my area with no results. Please help.